KR100190336B1 - Method of purifying bisphenol a, phenol crystalline adduct, method of producing the crystalline adduct, and method of producing bisphenol a. - Google Patents

Abstract

The present invention relates to a process for purifying crystal adducts.

The present invention relates to a method for depositing high quality crystal adducts having a low content of microcrystalline adducts in depositing crystal adducts in a crystal column, and separately recovering high quality crystal adducts from a crystal adduct slurry.

The present invention also relates to a crystallizer for depositing high quality crystal adducts.

The present invention also relates to a process for obtaining high quality bisphenol A, which is excellent in color and free from coloration of the melt in evaporating off the phenol contained therefrom from the crystal adduct.

The present invention also provides a high-quality product for producing bisphenol A by a phenol evaporation step of evaporating and removing phenol contained therefrom from a phenol solution containing bisphenol A, and steam stripping the phenol-containing bisphenol A obtained from the phenol evaporation step. It is about how to get A of efficiently.

Description

Method for purifying bisphenol A-phenol crystal adduct, method for preparing this crystal adduct, crystallizer therefor and method for producing bisphenol A

The present invention relates to a method for purifying high quality bisphenol A-phenol crystal adducts with good color, a method for producing this crystal adduct, a crystallization apparatus for the same, and a method for producing high quality bisphenol A.

It is known to react acetone with excess phenol in the presence of an acid catalyst to produce bisphenol A [2,2-bis (4'-hydroxyphenyl) propane]. In order to separate and recover high-purity bisphenol A from this reaction product, the reaction product is cooled to precipitate crystalline adducts of bisphenol A and phenol (hereinafter, also referred to simply as crystalline adducts) to remove phenol from the crystalline adduct obtained. It is also known as Japanese Command Office 36-23335, Command Office 62-42790.

In such a method for producing bisphenol A, since the purity and color of the bisphenol A recovered as a product largely depends on the purity and color of the crystal adduct, a high purity and good color crystal adduct is obtained. Is required.

In order to obtain a high-purity crystal adduct from a phenol solution containing bisphenol A obtained by reacting excess phenol with acetone, a series of combinations of the phenol solution through a plurality of crystallization steps and a separation and dissolution step of the crystal adduct in between. The method of processing by the crystallization process of is known.

In the conventional method for producing a crystal addition product using a plurality of crystallization processes, one crystal tower is used in the crystallization step of each stage, and a higher purity crystal additive can be obtained by increasing the number of crystallization steps in the crystallization step. have. In this case, however, if the number of crystallization steps is increased, the number of crystal adduct separation devices and crystal addition product dissolution tanks needs to be increased as the number of crystallization steps increases. Include a problem. In addition, by increasing the size of the crystallization tower, it is possible to obtain a high purity crystal adduct. However, when the size of the crystal tower is increased, the size of the cooling device, the crystal adduct circulator and the microcrystalline adduct dissolving tank also needs to be increased exponentially as the size of the crystal tower increases, and the crystal system is inefficient. It also includes the problem of larger size and higher device cost.

As a method for crystallizing a phenol solution containing bisphenol A and depositing a crystal adduct, a part of the crystal adduct slurry is extracted from the crystal tower, cooled by a cooler and recycled to the crystal tower. Maintaining the temperature of the crystallization tower at a predetermined crystallization temperature is performed. However, in this method, it is difficult to control the particle size of the crystal adduct in the slurry to be obtained, and the particle size distribution of the obtained crystal adduct varies greatly, and a crystal adduct containing a large amount of fine crystal adduct particles is obtained. On the other hand, since the fine particle-like crystal adduct is large in its surface area, it is easy to adsorb impurities which are coloring causing substances, and the obtained crystal adduct is poor in color. And bisphenol A obtained from such a crystal addition product also contains the substance which is its coloring source, and color becomes bad. Therefore, from the viewpoint of obtaining a high quality bisphenol A, a method for efficiently producing a crystal adduct slurry having a low content of microcrystalline adduct particles when crystallizing a phenol solution containing bisphenol A to obtain a crystal adduct slurry is obtained. It is important to develop it.

In order to obtain a high purity crystal adduct, it is known to filter a crystal adduct slurry obtained by crystallizing a phenol solution containing bisphenol A and to wash the separated crystal adduct with high purity phenol. In this case, by increasing the number of crystallization processes, product crystal adducts with increased purity can be obtained. However, in the production of crystal adducts including a plurality of crystallization steps, even if high purity phenol is used in each of the cleaning liquids for the crystal adduct cleaning obtained in each crystallization step, impurities having high adsorptivity such as colored substances may be removed from the crystal adducts. It is difficult to separate, so that a particular high purity of the crystal adduct is not achieved, but there is a problem that the cost for obtaining a large amount of its high purity phenol is high.

In the method for producing bisphenol A as described above, the purity and color of the bisphenol A recovered as a product greatly depend on the purity and color of the crystal adduct as described above, but the conditions for heating and melting the obtained crystal adduct, It is also greatly influenced by the conditions for evaporating the heated melt.

Separation of phenol from crystalline adducts is generally carried out by evaporation, extraction, stripping with water vapor or the like. As a method for removing phenol from the crystalline adduct by evaporation, specifically, as shown in Japanese Patent Application Publication No. 52-42790, after melting the crystalline adduct, it is vaporized at 0.1 to 30 minutes at a temperature higher than 180 ° C. and reduced pressure. The method of fractionally condensing and separating from bisphenol A, or the method of vapor-striping phenol containing bisphenol after removing a phenol by evaporating a crystal adduct at 180-200 degreeC (Patent No. 63-132850) are also known. However, the color of bisphenol A obtained by evaporating the phenol in the crystal adduct is deteriorated due to the heating in the evaporation treatment. For example, even if it is a crystal adduct having a good color of APHA 15 or less, the color of the product bisphenol A obtained by heating and melting it and evaporating off phenol from the melt deteriorates and usually exhibits APHA of 40 or more.

In order to solve this problem, a method of obtaining bisphenol A having an improved color by adding oxalic acid or citric acid to a phenol / water / bisphenol A mixture and then distilling it has been proposed (Special Publication No. 40-19333). In addition, a method of adding thioglycolic acid, glycolic acid, or polyphosphoric acid to improve the stability of bisphenol A (special publication No. 47-43937), or a method of adding lactic acid, malic acid, or glycerin acid (Japanese Patent Application Laid-Open No. 2-231444) Etc. are also known. However, also in these methods, the effect of the color improvement of bisphenol A was not enough.

On the other hand, in the method of steam stripping the phenol-containing bisphenol A obtained by evaporating and removing phenol from the crystal adduct, to obtain a high purity bisphenol A, a stripping gas consisting of phenol, bisphenol A and steam is obtained. This stripping gas is attached to the cooling condensation treatment, and bisphenol A and phenol are separated and recovered, but in this case, solids of bisphenol A or phenol are fixed on the base wall of the cooler as a scale, which significantly deteriorates the cooling efficiency of the cooler and at the same time. There is a problem such as blockage of.

One object of the present invention is to provide a method for purifying crystal adducts.

Another object of the present invention is to provide a method for efficiently preparing high quality crystal adducts.

It is still another object of the present invention to provide a method for depositing high quality crystal adducts having a low content of microcrystalline adducts in depositing crystal adducts in a crystal column.

It is another object of the present invention to provide a method for separating and recovering high quality crystal adducts from a crystal adduct slurry.

It is still another object of the present invention to provide a crystallization apparatus for depositing high quality crystal adducts.

It is still another object of the present invention to provide a method for obtaining bisphenol A having a high color and no coloration of a melt in preparing bisphenol A by evaporating and removing phenol contained therein from a crystal adduct.

It is still another object of the present invention to provide a method of preventing the coloring of bisphenol A by heating in the evaporation when producing bisphenol A by evaporating off the phenol contained therein from the crystal adduct.

Another object of the present invention is to produce bisphenol A by a phenol evaporation step of evaporating and removing phenol contained therefrom from a phenol solution containing bisphenol A, and by steam stripping the phenol-containing bisphenol A obtained from the phenol evaporation step. The present invention provides a method for efficiently obtaining high quality bisphenol A.

It is another object of the present invention to provide a method for condensing the stripping gas obtained in the stripping treatment of phenol-containing bisphenol A without depositing solid bisphenol A and phenol.

MEANS TO SOLVE THE PROBLEM The present inventors came to complete this invention as a result of earnestly researching in order to achieve the said objective.

According to the present invention, there is provided a method for producing purified phenol, wherein the industrial phenol having a water content of 0.5 wt% or less is brought into contact with a strong acid type ion exchange resin and then distilled at a temperature of 185 ° C. or less.

According to the present invention, a phenol solution in which bisphenol A is dissolved in a first crystal tower (A) of two crystal towers connected in series as a first process for preparing a crystal adduct. the supply and bisphenol ^a. A crystal addition product slurry containing seed crystals obtained in this crystallization step is precipitated at the same time as the seed crystal made of the crystal addition product of phenol is introduced into the second crystal tower (B), and the first crystal tower (A) is used. After carrying out crystal growth of the seed at low temperature, the crystal adduct slurry obtained in the crystallization step of this first stage is introduced into the solid-liquid separation process to separate the crystal adduct from the mother liquor, and then the crystal adduct is separated from the mother liquor. After re-dissolving with higher purity phenol, it is supplied to the first crystal tower (C) of two crystallization towers connected in series for performing the crystallization step of the second stage, and from the crystal adduct of bisphenol A-phenol. At the same time as depositing the seed crystals formed, the crystal adduct slurry obtained in this crystallization step is introduced into the second crystal tower (D), and crystal growth of the seed crystals is carried out at a lower temperature than the first crystal tower (C). Provided is a method for producing a bisphenol A-phenol crystal adduct _.

1 shows an example of an apparatus flow diagram when carrying out the first process of the present invention for producing a crystal adduct,

2 shows an example of an apparatus flow diagram when carrying out the second process of the present invention for producing a crystal adduct,

3 shows an example of a device schematic for carrying out the third process of the invention for producing a crystal adduct,

4 shows an example of an apparatus flow diagram when carrying out the fourth process of the present invention for producing a crystal adduct,

5 shows an example of a flow sheet in the case of carrying out the fifth process of the present invention for producing a crystal adduct,

FIG. 6 shows an example of an apparatus flow diagram when steam stripping a phenol solution containing bisphenol A,

7 shows an example of an apparatus flow diagram for condensing stripping gas,

8 shows another example of an apparatus schematic for condensing stripping gas.

Explanation of symbols on the main parts of the drawings

(In FIG. 1)

A, B, C, D: Crystal tower E: Solid-liquid separator

F: Crystal Additive Dissolution Tank P: Inner Cylinder

Q: Microcrystalline Adduct Melting Tank

(In FIG. 2)

A, B: crystal tower P: inner cylinder

Q: Microcrystalline Adduct Melting Tank

(In Figure 3)

1: outer cylinder 2: inner cylinder

3: microcrystalline adduct dissolution tank A: crystal tower

(In Figure 4)

A: 1st crystal tower B: 2nd crystal tower

3 to 4: first commercial cooler 5: preliminary cooler

6-7: 2nd commercial cooler 8-13: Pump

101-107: crystallization liquid transfer line

(In FIG. 5)

A-1, A-2, A-3: Crystallization Process

B-1, B-2, B-3: solid-liquid separation process

C-1, C-2: remelting process

(In FIG. 6)

1,2,3: Thin Film Evaporator

4: external heater

(In FIG. 7)

21: first cooler

22: second cooler

(In FIG. 8)

21: first cooler

22: second cooler

41: cooler

45: partition plate

According to the present invention, as a second process for the production of crystal adducts, bisphenol A. is obtained by using n (n ≧ 2) crystal towers having inner cylinders with openings thereon ^. In the method for producing a phenol crystal adduct,

(a) precipitate bisphenol A-phenol crystal adducts in each crystal column to form a crystal adduct slurry;

(b) extracting the crystalline adduct slurry from the bottom of the inner cylinder of each crystal tower;

(c) cooling a part of each extracted crystal adduct slurry and circulating it in each crystal tower,

(d) Among the crystal columns of the first to nth stages, a part of the crystal adduct slurry extracted from the crystal column of the at least nth stage is heated to dissolve the microcrystalline adduct particles contained in the crystal adduct slurry. After that, the circulation is introduced into the crystal tower,

(e) adding a raw material solution consisting of a phenol solution containing bisphenol A to the cooled crystal addition slurry circulated in the crystallization column of the first stage, and feeding the crystallization column of the first stage;

(f) A portion of the crystal adduct slurry extracted from the inner bottom of each crystal tower of the first stage to the (n-1) stage is added to the circulating cooling line of the crystal adduct slurry in each subsequent crystal tower. Supplies to the next step of the crystal tower,

(g) Recovering a part of the crystal adduct slurry extracted from the inner bottom of the crystal column of the nth stage or a part of the heated circulation slurry in the nth stage as a product crystal adduct slurry

A method for producing a bisphenol A phenol crystal adduct is provided.

According to the present invention, a phenol solution containing bisphenol A is supplied into the outer cylinder of the crystal structure column of double structure in which the inner cylinder with the opening is inserted into the outer cylinder of the closed structure as a third process for producing the crystal adduct. The bisphenol A-phenol crystalline adduct slurry was extracted from the inner bottom of the crystal tower, and a part of the extracted crystalline adduct slurry was cooled and circulated and introduced into the outer cylinder so as to generate swirl flow. A part of the crystalline adduct slurry thus prepared is heated, and the microcrystalline adduct particles contained in the crystalline adduct slurry are dissolved, and then circulated in the outer cylinder so that a swirl flow in the same direction as the cooling crystal adduct slurry occurs from the bottom of the outer cylinder. At the same time, a part of the crystal adduct slurry extracted from the inner cylinder bottom or the microcrystal contained in the crystal adduct slurry A portion of the additional decision after dissolving the heat of the particles of water slurry, the product crystals are added to provided a method for producing bisphenol A · phenol adduct crystal slurry, characterized in that for recovering a water slurry.

According to the present invention, as a fourth process for producing a crystal adduct, a crystal tower and a cooler are prepared, and a part of the crystal adduct slurry is extracted from the crystal tower, cooled by the cooler, and the cooled crystal adduct slurry is obtained. In the crystallization method in which the crystal adducts are precipitated in the crystal tower by recirculating to the crystal tower, and the precipitated crystal adducts are extracted from the crystal tower and separated from the crystal adduct slurry. One of the condenser coolers is used as a preliminary cooler, and only the cooler other than the preliminary cooler is used to cool the crystal adduct slurry, and the cooler in which the heat transfer efficiency of the crystal adducts deposited on the heat transfer surface is reduced is replaced with the preliminary cooler. At the same time, by heating a cooler whose heat transfer efficiency is lowered, it dissolves and regenerates the crystal adduct attached to the heat transfer surface. This bisphenol A · phenol crystals addition method of water is produced, characterized in service.

According to the present invention, as a fifth process for producing a crystal adduct, a phenol solution containing bisphenol A is prepared in a crystallization step of n (n ≧ 2) steps, a solid-liquid separation step of n steps, and at least one step of bisphenol A. A crystal adduct obtained by solid-liquid separation of the crystallization product obtained in the crystallization step of each step of the n-th step from the first step including the phenol crystal adduct washing step and the crystallization of the n-1 step; Or washed with a washing solution and redissolved with phenol solution to be supplied to the next step of crystallization, and the crystallization product obtained in the nth step of crystallization is subjected to solid-liquid separation. In the method of obtaining water,

(a) using purified phenol for at least part of the washing liquid of the nth crystal adduct obtained in the solid-liquid separation process of the nth stage,

(b) at least a part of the phenol solution for re-dissolving the crystalline adducts obtained in the solid-liquid separation process of the n-th stage at least, in the washing liquid drainage of the crystalline adducts obtained in the solid-liquid separation process of the n-th stage, or in the solid-liquid separation process of the n-th stage Using the obtained mother liquor,

(c) at least a part of the cleaning liquid obtained in the solid-liquid separation process of the solid-liquid separation process of the n-th stage, and washing liquid drainage of the mother liquor obtained in the solid-liquid separation process of the n-th stage or the solid-liquid separation process of the n-th stage.淨 排 液),

(d) Crystal adducts in the next stage, both the impurity concentration in the phenol solution for re-dissolution and the impurity concentration in the crystal adduct cleaning liquid in each stage from the first stage to the n-1 th stage A method for producing bisphenol A-phenol crystal adducts is provided which is higher than the impurity concentration in the re-dissolving phenol solution and the impurity concentration in the crystal adduct cleaning liquid.

According to the present invention, a bisphenol A-phenol crystal adduct slurry obtained by crystallizing a phenol solution containing bisphenol A as a sixth process for producing a crystal adduct is subjected to filtration, and has a particle size of 100 µm in the crystal adduct. A part of the following microcrystalline adduct component is transferred to the filtration side, and the ratio of the microcrystalline adduct component of 100 micrometers or less in particle size collect | recovers the coarse crystal adduct of 20 weight% or less, The bisphenol crystal adduct A manufacturing method is provided.

According to the present invention, as a crystallizer for producing a crystal adduct, a crystal tower and a plurality of coolers are provided, and the crystal tower has a crystal adduct slurry return port at a position other than its bottom, and a crystal adduct slurry outlet at its bottom; Each of the clusters has an inlet and an outlet, respectively, between the crystal adduct slurry outlet of the crystal tower and the inlet of each cooler, and between the return port of the crystal adduct slurry and the outlet of each cooler, respectively. And the crystal adduct slurry is transferred from the crystal adduct slurry outlet of the crystallite tower to the crystal adduct slurry return port of this crystal tower selectively via a cooler excluding any one of the coolers of this condenser. The apparatus for obtaining the made bisphenol A phenol crystal adduct is provided.

According to the present invention, as a first process for obtaining bisphenol A, the crystal adduct under substantially neutral conditions of molten color APHA 15 or less composed of bisphenol A and phenol is heated to a condition of oxygen concentration of 0.005 vol% or less in the atmosphere. There is provided a process for producing a high quality bisphenol A characterized by evaporating and removing phenol from the melt obtained while melting.

According to the present invention, as a second process for obtaining bisphenol A, a mixture containing a crystal adduct and aliphatic carboxylic acid having a molten color APHA composed of bisphenol A and a phenol under substantially neutral conditions of 15 or less has a temperature of 130 to Provided is a method for producing a high quality bisphenol characterized in that the phenol is evaporated off at 200 ° C. under reduced pressure.

According to the present invention, a third process for obtaining bisphenol A is composed of bisphenol A and phenol, and the molten color APHA under weakly acidic conditions containing a strongly acidic substance is added an aliphatic carboxylic acid salt to a crystal adduct of 15 or less. Provided is a method for producing a high quality bisphenol, wherein the phenol is evaporated and removed at a temperature of 130 to 200 ° C. under reduced pressure after the addition and mixing of the strong acidic substance in the crystal adduct.

According to the present invention, as a fourth process for obtaining bisphenol A, a molten color APHA is supplied with a crystal adduct of bisphenol A having a phenol of 15 or less and phenol to an apparatus system including a melting apparatus and an evaporation apparatus, and in this melting apparatus A method of melting a crystalline adduct and evaporating the crystalline adduct melt in this evaporator to separate bisphenol A and phenol from each other, wherein at least the amount of oxygen adhering to the inner wall surface of the melting apparatus and the evaporation apparatus included in the apparatus system. Is removed to 10 mmol or less per 1 m ² of the inner wall by organic solvent washing, and then a crystal adduct is supplied to the apparatus system, and a process for producing high-quality bisphenol A is provided.

According to the present invention, as a fifth process for obtaining bisphenol A, the molten color APHA has a melt of a product of crystal adducts of bisphenol A with phenol of 15 or less and at least one evaporation column having a member for improving the evaporation surface therein. When the phenol is evaporated and removed under reduced pressure, the oxygen adhering to the inner wall surface of the evaporation tower and the member surface which improves the evaporation surface area disposed inside the evaporation tower is 10 millimoles per 1 m ² of surface area. Provided is a method for producing a high quality bisphenol A characterized by using an evaporation tower previously removed.

According to the present invention, as a sixth process for obtaining bisphenol A, when phenol is evaporated off from bisphenol A-phenol crystal adduct to obtain bisphenol A, the phenol solution containing bisphenol A formed from this crystal adduct is thin film evaporator. Phenol evaporation process to obtain bisphenol A having a phenol content of 1 to 5% by weight by evaporation at a temperature of 160 to 185 ° C. and a pressure of 15 to 60 torr, and the phenol obtained in this phenol evaporation step. A bisphenol A containing a phenol obtained in the second stripping step of stripping the bisphenol A by countercurrent contact with the stripping gas at a temperature of 170 to 185 ° C. and a pressure of 15 Torr or less. The first stripping, which is subjected to the stripping treatment by countercurrently contacting the stripping gas at a temperature of 170 to 185 ° C. and a pressure of 15 Torr or less And a phenol and bisphenol A obtained in the second stripping step, comprising steam, using steam as the stripping gas in the first stripping step, and the stripping gas in the first stripping step. Provided is a method for producing a high quality bisphenol A, characterized by using a stripping gas consisting of steam.

According to the present invention, as a seventh process for obtaining bisphenol A, pisphenol A having a melt color of 15 APHA or less under substantially neutral conditions ^. The phenol solution containing bisphenol A formed from the phenol crystal adduct was evaporated using a thin film evaporator at a temperature of 160 to 185 ° C. and a pressure of 15 to 60 torr under conditions of an oxygen concentration of 0.005 vol% or less in the atmosphere. The phenol evaporation step of obtaining bisphenol A having a content of 1 to 5% by weight, and the bisphenol A containing phenol obtained in the phenol evaporation step are brought into countercurrent contact with the gas for stripping at a temperature of 170 to 185 ° C and a pressure of 15 Torr or less. Stripping treatment is carried out by stripping the first stripping process and bisphenol A containing phenol obtained in the first stripping process by countercurrently contacting the stripping gas at a temperature of 170 to 185 ° C. and a pressure of 15 torr or less. A second stripping step, wherein steam is used as the stripping gas in the first stripping step; As a stripping gas in the stripping process, there is provided a method for producing high-quality bisphenol A, characterized by using a stripping gas composed of steam containing phenol and bisphenol A obtained in the second stripping process.

According to the present invention, as an eighth process for obtaining bisphenol A, stripping containing a phenol compound, bisphenol A and steam obtained when steam stripping of a mixed melt of phenol and bisphenol under low pressure conditions of 30 Torr or less is performed. A method of condensing a gas, comprising: phenol or bisphenol A containing the stripping gas under low pressure conditions up to 30 Torr and under temperature conditions in which the vapor is maintained as a gas and a portion of the phenolic compound is held in liquid. A first cooling step of countercurrently contacting the first cooling medium made of phenol to condense a substantial amount of bisphenol A contained in the stripping gas and a part of the phenol, and at the same time obtain a mixed gas of uncondensed vapor and phenol; The mixed gas obtained in the first cooling step is condensed under a low pressure condition of 30 Torr or less and substantially the entire amount of the mixed gas. Provided is a condensation treatment method for a stripping gas comprising a second cooling step in which the second cooling medium is made countercurrently contacted with a second cooling medium made of an aqueous solution of phenol to condense substantially the entire amount of the mixed gas.

Next, the method for purifying the crystal adduct according to the present invention will be described in detail.

In the method for purifying the crystal adduct of the present invention, the reaction product of (i) industrial phenol, (ii) phenol and acetone, (iii) concentration step of the reaction product, for the crystal adduct of bisphenol A and phenol, (iv) Crystallization Step of Phenol Containing Bisphenol A At least one phenol selected from the phenols obtained in the washing step of the adduct is washed using a purified phenol purified by a specific method. The present inventors earnestly studied about the purification method of the said phenol itself in order to obtain the phenol suitable for washing | cleaning a crystalline adduct, As a result, after contacting this phenol with strong acid type ion exchange resin, the phenol refined product obtained by evaporation process is The product bisphenol A obtained by washing the crystal adduct using this purified phenol and removing the phenol from the washed crystal adduct without containing a coloring causative substance which lowers the color of the product bisphenol A has a very low colorability. It was found.

The phenol used for washing the crystal adduct in the present invention comprises at least a part of a crystallization product of (i) an industrial phenol, (ii) a phenol separated from the reaction product of phenol and acetone, and (iii) a phenol containing bisphenol. Purified product of at least one phenol selected from the separated phenols and (iv) used phenols after washing the crystal adduct is used.

As industrial phenols, those having a phenol purity of 99.5% by weight or more are commercially available, but in the present invention, purified products of these phenols can be used.

In the reaction product obtained by the reaction of phenol and acetone, in order to concentrate the produced bisphenol A contained therein, phenol is separated from the reaction product, but in the present invention, a purified product of the separated phenol can be used.

When crystallization of a phenol containing bisphenol A is crystallized to precipitate crystal adducts, a plurality of stages of crystallization and solid-liquid separation of crystallization products are usually employed, thereby obtaining a plurality of mother liquors (phenols). In the invention, a purified product of phenol that forms these mother liquors can be used. The mother liquor purified product used in the present invention may be a purified product of any mother liquor of these mother liquors, but preferably, a mother liquor purified product separated from the crystallization product obtained in the most advanced crystallization step is used.

In the present invention, after washing the crystal adduct, a used phenol is obtained. However, in the present invention, a purified product of the used phenol can be advantageously used.

As a raw material phenol for obtaining the said phenol refined used by this invention, the use of the thing whose purity is 99 weight% or more, Preferably it is 99.5 weight% or more is preferable.

When the phenol is purified, the raw material phenol is first treated by contact with a strong acid type ion exchange resin, but in this case, those having a sulfone group are used as the strong acid type ion exchange resin. Examples of the strong acid type ion exchange resin include sulfonated styrene-divinyl benzene copolymers, sulfonated crosslinked styrene polymers, phenol-formaldehyde-sulfonic acid resins, and benzene-formaldehyde-sulfonic acid resins. All of these resins have a crosslinked structure and are insoluble. The strong acid type ion exchange resin is known to be a gel type or a macroporous type, and in the present invention, use of a gel type, which can be used, is preferable. The macroporous type is different from the gel type, and when used as a catalyst, the activity decreases with time, and therefore its use is not very preferable. In the gel strong acid type ion exchange resin, the degree of crosslinking (% by weight of the crosslinking agent contained in the resin) is 10% or less, preferably 5% or less. Preferred gel-type strong acid ion exchange resins to be used in the present invention are, for example, Amberlite and Amberlyst available from Rohm Haas Company, or from Mitsubishi Chemical Corporation. Diamond ion (DIAION) etc. which can be mentioned are mentioned. The treatment of phenol using this strong acid type ion exchange resin can be carried out by a method of circulating phenol in a packed column containing a strong acid type ion exchange resin, or by adding a phenol to a stirring tank containing a strong acid type ion exchange resin and stirring the mixture. There is a number. Treatment temperature is 45-150 degreeC, Preferably it is 50-100 degreeC. The contact time of the strong acid type ion exchange resin and phenol is 5 to 200 minutes, preferably about 15 to 60 minutes. When processing phenol using this strong acid type ion exchange resin, the moisture in phenol is 0.5 weight% or less, Preferably it is 0.1 weight% or less. If there is more moisture than this, the impurity conversion effect by a strong acid type ion exchange resin worsens. Removal of water up to 0.5% by weight from phenol can be carried out by azeotropic addition of a known azeotropic agent to the phenol.

The phenol contacted with the strong acid type ion exchange resin contains a high boiling point impurity in which impurities are inverted, and the high boiling point impurity is separated as a distillation residue by distillation.

The operating conditions of the distillation column should be able to separate the phenol and high boiling point impurities, but it is necessary to carry out under the condition that the high boiling point impurities are not mixed in the distilled phenol, and it is important to keep the distillation treatment temperature below 185 ° C. . If the temperature is 185 DEG C or lower, the operating pressure is arbitrarily set, but is usually performed under a reduced pressure of 50 Torr to 600 Torr. If the operating temperature is higher than 185 ° C, decomposition of high boiling point impurities or the like occurs, which degrades the quality of the purified phenol.

Purified phenol obtained by the above treatment has an APHA standard color of 10 or less and does not particularly deteriorate its color even if adhered to the product bisphenol.

The washing | cleaning of a crystal addition product with refined phenol should just be a method which can fully achieve contact with a crystal addition product and a refined phenol. This washing treatment is, for example, a method in which a mother liquor is removed from the crystal addition product in a solid-liquid separation device such as a filter or a centrifugal separator for separating the crystal addition product, followed by introduction of the purified phenol into the solid-liquid separation device for cleaning. The crystal adduct to which the small amount of mother liquor discharged | emitted from a separation apparatus adheres can also be wash | cleaned with refined phenol in a separate stirring tank. The use ratio of the refined phenol to the crystalline adduct is in the ratio of 30 to 1000 parts by weight, preferably 100 to 300 parts by weight, based on 100 parts by weight of the crystalline adduct.

The crystal adducts washed with the above-described purified phenols are those to which the purified phenols adhere to the surface, but are themselves sent to the phenol removal process from the crystal adducts, where the phenols are removed and the high-purity product bisphenol A is recovered. Removal of phenol from the crystalline adduct can be carried out by a conventionally known method such as distillation, extraction, steam stripping, or the like.

According to the purification method of the crystal addition product of this invention, the product bisphenol A which is excellent in color can be obtained. This invention has the following advantages because it uses the refined product of specific phenol as a washing | cleaning liquid of a crystal addition product.

(1) Since the adduct which does not contain an impurity, especially the impurity which causes coloring, is obtained, the product bisphenol which is high purity and low colorability excellent in color is obtained.

(2) Since no solvent is mixed in the cleaning liquid, the cleaning liquid can be circulated and used in the reaction system or crystallization system as it is.

The refined phenol used in the present invention is suitable as a cleaning liquid of the crystalline adduct between phenol and bisphenol A as described above. However, since the purified phenol is a high purity having excellent color, various phenol derivatives having good color, such as alkylphenol or phenol resin, etc. It is also suitable as.

In addition, by adding a small amount (0.0001 to 0.01 wt%) of oxalic acid or citric acid to the purified phenol obtained in the present invention, it is possible to suppress the deterioration of its color in storage and reaction.

Next, the manufacturing method of the crystal additive of this invention is demonstrated.

(First process)

1 shows an apparatus flow diagram when carrying out the first process for the production of crystal adducts according to the invention. In this figure, A, B, C, and D denote a crystal tower, E denotes a solid-liquid separator and F denotes a dissolution tank.

In each crystal tower A, B, C, and D, the inner cylinder P which has an opening part in the upper part is inserted and installed. In addition, microcrystalline adduct dissolution tank Q is provided in each crystal tower A, B, C, and D. The crystal towers A and B are connected in series to form an apparatus system for performing the first stage crystallization process, and the crystal towers C and D are connected in series to form an apparatus system for performing the crystallization process of the second stage. do.

Phenol solution containing the raw material, bisphenol A to be processed is fed to the line 1 and the line 2 the two positive pagoda connected in series via A, the lower portion of the first information pagoda A in B, where ^bisphenol-A. Seeds composed of phenol crystal adducts are precipitated. In this crystal tower A, the phenol solution containing the crystal addition product (termination) of the upper part in the tower flows out in the inner cylinder P, and it is taken out through the line 3, and the pump 4, the line 5, and the cooler Through (6) and line (2) it is circulated into the first crystal tower A, whereby the phenol solution in the crystal tower A is cooled and the crystal tower A is cooled to a predetermined temperature.

Some of the crystalline adduct slurry (hereinafter simply referred to as slurries), which are crystallization products comprising seed extracted from the inner cylinder P in the crystal tower A, are referred to as lines 7, pump 8, line 9, line 10 and The furnace 11 is introduced into the microcrystalline adduct dissolution tank Q where a slurry containing the crystals of coarse crystals of constant size is dissolved and the fine crystals in the crystal adduct are dissolved at the bottom of the crystallization tower A through line 13. This makes it possible to make the grains of the seed crystals contained in the crystal tower A evenly, thereby producing seed crystals with low seed crystal content and high seed crystal content in the coarse crystal.

The microcrystalline adduct in the crystallization tower A has a large specific surface area and shows high adsorption with respect to a coloring causative substance. Therefore, a seed with good color can be obtained by reducing the particle content of the microcrystalline component in the crystal adduct obtained as seed crystal in the crystal tower A as much as possible. According to the researches of the present inventors, it is found that high purity crystal adducts having good color can be produced by maintaining the particle content of the microcrystalline component having a particle diameter of 100 μm or less in the crystal adduct at 30% by weight or less, preferably 20% by weight or less. It became.

The phenol solution containing bisphenol A used as a raw material to be treated in the present invention usually contains bisphenol A: 7 to 50% by weight, preferably 10 to 30% by weight, and other components such as isomers of trisphenol A, trisphenol and the like 8 It is included in the ratio of weight% or less.

The temperature of the phenol solution containing bisphenol A supplied by the line (1) is a temperature about 1-20 degreeC higher than the saturation temperature of a crystal addition product. The crystallization temperature of the crystallization tower A is 45-70 degreeC, Preferably it is 48-57 degreeC. The slurry circulated through the line 3, the pump 4, the cooler 6, and the line 2 is lowered in the cooler 6 by about 10 ° C or less, preferably about 5 ° C or less. The residence time of the phenol solution in the crystal tower A is 0.5 to 10 hours, preferably 0.5 to 5 hours.

On the other hand, the slurry introduced into the microcrystalline adduct dissolution tank Q through the line 7, the pump 8, the line 10, and the heater 11 is heated at about 0.5 to 5 ° C. in the heater 11. Lose. The residence time of the phenol solution in this tank Q is about 3 to 15 minutes.

In the microcrystalline dissolution tank Q, microcrystalline adducts having a particle size of 100 μm or less are mainly dissolved, and the slurry in which the microcrystalline adducts are dissolved is returned to the crystal tower A through the line 13, whereby growth of crystals in the crystal tower A is prevented. It is promoted and the end of coarse crystal is obtained.

A portion of the slurry extracted from the bottom of the inner cylinder P in the first crystal tower A is introduced into the lower portion of the first crystal tower B through the line 7, the pump 8, the line 12 and the line 21, and here Growth of crystal adducts takes place. This second crystal tower B is operated in the same manner as described with respect to the crystal tower A.

In the crystal tower B, the temperature range is 45-70 degreeC, and is maintained about 3-10 degreeC lower than the crystallization temperature of the crystal tower A. The slurry passed through the cooler 26 is lowered at about 10 ° C or less, preferably about 5 ° C or less.

On the other hand, the temperature of the slurry through the heater 31 is raised about 0.5-5 degreeC here.

In the microcrystalline adduct dissolving tank Q placed in the crystal tower B, a crystal adduct component having a particle size of 100 μm or less is dissolved, and the slurry in which the microcrystalline adduct is dissolved is returned to the crystal tower through the line 33 so that the growth of the crystal is reduced. Is promoted. The concentration of the crystal adduct in the slurry extracted from the bottom of the inner cylinder P in the crystal tower B is 35% by weight or less, preferably 25% by weight or less, and the particle content of the microcrystalline component having a particle size of 100 μm or less in the crystal adduct is 30% by weight. Or less, preferably 20% by weight or less.

A part of the slurry extracted from the bottom of the inner cylinder P in the second crystal tower B is introduced into the solid-liquid separation device E through the line 35, where the crystal adduct and the mother liquor are separated, and the separated crystal adduct is line ( 36) is introduced into the crystal adduct dissolution tank F, where it is dissolved again.

As the solid-liquid separator E, a conventionally known one, for example, a centrifuge or a filtration device is used. As a dissolution tank F, a conventionally well-known thing, for example, the stirring tank which has a stirrer inside, and a heating type dissolution tank are used.

In the dissolution tank F, it is preferable to introduce purified phenol from the line 81 and to dilute and dissolve the crystal adduct under stirring using this purified phenol. In this case, heating can also be used together as needed. The temperature of a dissolution tank is 70-160 degreeC, Preferably it is 80-100 degreeC. As the purified phenol, one whose purity is higher than that of the mother liquor is used.

When diluting and dissolving a crystal adduct with a refined phenol, the refined phenol may be any one as long as the content of the impurity which does not cause coloring of the product bisphenol A is small. As the refined phenol which can be preferably used in the present invention, various refined phenols described in the above-described purification method of the crystal adduct may be mentioned.

Such purified phenols have an APHA standard color of 10 or less and do not particularly deteriorate their color even if they are attached to the crystal adduct and the product bisphenol A.

The phenol solution containing bisphenol A from the dissolution tank F is introduced into the lower portion of the first crystallization column C constituting the crystallization system of the second stage through the line 41. In this case, the concentration of the phenol solution is adjusted so that the concentration of bisphenol A is 7 to 50% by weight, preferably 10 to 30% by weight.

This crystal tower C is operated similarly to the crystal tower A shown above. In the crystal tower C, the crystallization temperature is 45-70 degreeC, and is maintained about 0-10 degreeC higher than the temperature of the crystal tower A. The slurry passed through the cooler 46 is lowered at a temperature of about 10 ° C. or less, preferably about 5 ° C. or less.

On the other hand, the temperature of the slurry through the heater 51 is raised about 0.5-5 degreeC here.

In the microcrystalline adduct dissolving tank Q placed in the crystal tower C, the microcrystalline adduct component having a particle size of 100 μm or less is dissolved, and the slurry in which the microcrystalline component is dissolved is returned to the crystal tower C through the line 53 to promote its growth. do.

A portion of the slurry extracted from the bottom of the inner cylinder P in the crystal tower C is introduced into the lower portion of the second crystal tower D which constitutes the crystallization system of the second stage through the lines 52, 61, and 62, and Here, crystal growth takes place.

This second crystal tower D is operated in the same manner as the crystal tower A described above. In crystal tower D, the crystallization temperature is 45-70 degreeC, it is 0-10 degreeC lower than the temperature of crystal tower C, and it is maintained about 0-10 degreeC higher than crystal tower B.

On the other hand, the temperature of the slurry through the heater 71 is raised about 0.5-5 degreeC here.

In the microcrystalline adduct dissolving tank Q placed in the crystal tower D, the microcrystalline adduct component having a particle size of 100 µm or less is dissolved, and the slurry in which the microcrystalline component is dissolved is returned to the crystal tower through line 73 to grow the crystals. Is done. The concentration of the crystal adduct in the slurry extracted from the bottom of the inner cylinder P in the crystal tower D is 35% by weight or less, preferably 25% by weight or less, and the content of the microcrystalline adduct component having a particle size of 100 μm or less in the crystal adduct is 30% by weight. % Or less, preferably 20% by weight or less.

The slurry extracted from the bottom of the inner cylinder P in the crystal tower D is recovered as a product slurry through the line 80. This slurry is solid-liquid-separated as needed, and the obtained crystal addition product is sent to the bisphenol A collection | recovery process, a phenol is removed, and bisphenol A is collect | recovered.

According to the first process for obtaining a crystal adduct according to the present invention, a bisphenol A-phenol crystal adduct with high purity and good color of APHA 15 or less can be obtained in high yield.

This bisphenol A phenol crystal adduct removes and removes a phenol from this, and gives bisphenol A of high purity and color.

(Second process)

Next, a second process for obtaining a crystal adduct according to the present invention will be described with reference to the drawings.

2 shows an apparatus flow diagram when carrying out the present invention using two (n = 2) crystal towers. In this figure, A represents the crystal tower of the first stage, and B represents the crystal tower of the second stage.

In each crystal tower A, B, the inner cylinder P which installed the opening part in the upper part is inserted and installed. In addition, each crystal tower A and B is provided with the microcrystalline adduct dissolution tank Q.

In each crystal tower A, B which is normally operating, crystal addition product precipitates in the inside, and the slurry of crystal addition product is formed. In addition, from the bottom of the inner cylinder P of the crystallization towers A and B, the crystalline adduct slurry is discharged to the outside through each of the lines 3 and 23, a part of which is each of the pumps 4, 24 and 5 ), (25), and coolers (6), (26), and lines (2) and (22) are circulated into each crystal tower A and B, whereby the slurry in the crystal towers A and B is cooled to Each crystal tower A, B is cooled by predetermined temperature.

In addition, a part of the slurry including the crystal adducts extracted from the inner cylinder P in each of the crystal towers A and B is line (7), (27), pump (8), (28), line (9), (29), Lines 10, 29 and heaters 11, 31 are introduced into the microcrystalline adduct dissolution tank Q, where the microcrystalline particles in the crystal adduct are dissolved and comprise coarse crystal adducts of constant size. The slurry to be circulated through the lines 13 and 33 to the lower portions of the crystallization towers A and B, whereby the grain diameters of the crystal additives contained in the crystallization towers A and B are evened, and thus, the crystallization additions are added to the crystallization towers A and B. A crystal adduct having a low water particle content rate and a high coarse crystal adduct content rate is produced. The operation of circulating the crystalline adduct slurry in the dissolution tank Q and then circulating to the crystallization tower may be performed at least in the final stage, and may be omitted in the crystallization tower of other stages as necessary.

The microcrystalline adduct in the crystal towers A and B has a large specific surface area and shows high adsorption to the coloring agent. Therefore, the crystal addition product of a good color can be obtained by reducing the content rate of the microcrystal addition product particle in the crystal addition product obtained by crystal towers A and B as much as possible. According to the researches of the present inventors, it was found that high purity crystal adducts with good color can be produced by maintaining the content of microcrystalline adduct particles having a particle diameter of 100 μm or less in the crystal adducts at 30% by weight or less, preferably 20% by weight or less. It became.

External cylinder from bottom of outer cylinder of crystal towers A and B when circulating introduction of the temperature lowered slurry through lines (2) and (22) and the slurry with temperature rise through lines (13) and (33) into crystal towers A and B The swirl flows in the same direction inward. In this case, Preferably it introduces so that it may become tangential with respect to an outer cylinder inner peripheral surface, and it is performed so that the introduction position may differ. In addition, the introduction position of these two slurries is represented by the angle from the center point of an outer cylinder, Preferably it is good to carry out in the position which is 90-180 degree away. In addition, if the two flow directions are to be generated in the same direction, the introduction positions of the two slurries do not necessarily have to be on the same horizontal line, and there may be some height difference at least in the lower part of the outer cylinder.

As described above, the respective slurries passing through the lines (2), (22), and the lines (13) and (33) are introduced into the crystal towers A and B such that the introduction direction thereof is tangential to the inner circumferential surfaces of the crystal towers A and B. While the swirl flow is generated in the slurry in the crystal towers A and B, the swirl flow rises up to the upper end of the inner cylinder P, and then descends the inner cylinder P from the opening of the upper portion of the inner cylinder P, from the bottom of the inner cylinder P. It is released.

By producing such swirling flows in the crystal towers A and B, the following effects can be obtained.

(1) Two liquid streams of different temperatures can be effectively and uniformly mixed.

(2) Since dispersion of the slurry is prevented and the slurry concentration in the outer cylinder is uniform, nonuniformity of residence time in the outer cylinder of the crystal addition product particles can be eliminated.

(3) A sufficient linear velocity can be obtained to prevent sedimentation deposition in the outer cylinder of the crystal adduct particle.

In this invention, the raw material liquid which consists of a phenol solution containing bisphenol A is added to the cooled slurry through the cooler 6 circulated to the crystal tower A of the 1st stage, and is supplied to the crystal tower A of the 1st stage.

In the present invention, a part of the slurry extracted from the bottom of the inner cylinder P of the crystallization tower A of the first stage is added to the slurry cooled through the cooler 26 circulated to the crystallization tower B of the second stage and the second stage It is supplied to the crystal tower B of. By supplying the slurry obtained from the crystallization tower A of the first stage in this way to the crystallization tower B of the first stage, efficient cooling of the feed slurry is achieved and cooling heat is used for the growth of crystal adduct particles to reduce the supersaturation of the liquid. Thus, advantages such as an increase in the particle size distribution of the crystal adduct particles can be obtained.

The temperature of the phenol solution containing bisphenol A supplied from the line (1) is 1-20 degreeC higher than the saturation temperature of an adduct, and the temperature of the crystallization tower A is 45-70 degreeC. The slurry circulated through the line 3, the pump 4, the cooler 6 and the line 2 is lowered in the cooler 6 at a temperature of about 10 ° C or less, preferably about 5 ° C or less. The residence time of the phenol solution in the crystal tower A is 0.5 to 10 hours, preferably 0.5 to 5 hours.

On the other hand, the slurry introduced into the microcrystalline adduct dissolving tank Q through the line 7, the pump 8, the line 10, and the heater 11 is raised in the heater 11 by about 0.5 k to 5 ° C., and thus, uncrystallized. The adduct is kept in the melting tank Q. The residence time of the slurry in this tank Q is about 3 to 15 minutes.

In the microcrystalline dissolution tank Q, a crystal adduct having a particle size of 100 µm or less is dissolved, and the slurry in which the microcrystalline is dissolved is returned to the crystallization tower A through the line 13 to promote crystal growth.

A part of the slurry extracted from the bottom of the inner cylinder P in the crystal tower A of the first stage is passed through the line 7, the pump 8, the line 12 and the line 21, and then through the cooler 26. It is added to the slurry circulated to B and introduced into the crystal tower B of the second stage. The crystal tower B of the second stage is operated in the same manner as described with respect to the crystal tower A.

The temperature of the crystal tower B is maintained at a temperature 3 to 10 ° C. lower than the temperature of the crystal tower A.

On the other hand, the slurry which passes through the heater 31 raises the temperature here about 0.5-5 degreeC, and the temperature of the microcrystal addition product dissolution tank Q which was attached to the crystallization tower B by this is 0.5-5 degreeC than the temperature of the crystallization tower B. It is maintained at a high temperature.

In the microcrystalline adduct dissolution tank Q placed in the crystal tower B, crystal adducts having a particle diameter of 100 μm or less are dissolved, and the slurry in which the microcrystals are dissolved is returned to the crystal tower B through the line 33 to grow crystals of the crystal adduct. This is facilitated. The concentration of the crystal adduct in the slurry extracted from the bottom of the inner cylinder P in the crystal tower B is 35% by weight or less, preferably 25% by weight or less, and the content of microcrystalline adduct particles having a particle size of 100 μm or less in the crystal adduct is 30% by weight. Or less, preferably 20% by weight or less.

A part of the slurry extracted from the bottom of the inner cylinder P in the second crystal tower B is recovered as the product slurry through the line 35. This slurry is solid-liquid-separated as needed, and the obtained crystal addition product is sent to the bisphenol A collection | recovery process, a phenol is removed, and bisphenol A is collect | recovered.

The product slurry can be extracted from the bottom of the inner cylinder P of the second stage as described above, and a part of the heated circulating slurry circulated from the microcrystalline adduct dissolution tank Q through the line 33 to the crystallization tower B as the product slurry. It can also be recovered.

In FIG. 2, although the apparatus flow diagram in the case of implementing the method of this invention using two crystal towers A and B is shown, it can carry out similarly even if more crystal towers are used. That is, when performing crystallization using n (n ≥ 2) crystallization towers, the raw material solution is added to the cooled crystal addition slurry circulated to the crystallization tower of the first stage and supplied to the crystallization tower of the first stage, A portion of the crystalline adduct slurry extracted from the inner cylinder bottom of each crystal tower from the first stage to the (n-1) stage is added to the circulating cooling slurry in the crystal tower of the next stage and added to the crystal tower of the next stage. After the supply, a part of the crystal adduct slurry extracted from the inner cylinder bottom of the nth stage (final stage) crystal tower or a part of the heated circulation slurry in the nth stage crystal tower is recovered as a product slurry. In this case, the temperature of the crystallization tower maintains the highest temperature of the crystallization tower of the first stage and the temperature of the crystallization tower of the nth stage at the lowest temperature, but is sequentially lowered from the first stage to the nth stage. . The temperature difference between each crystal tower and the crystal column of each next stage is 3-10 degreeC, Preferably it is 5-8 degreeC, and the temperature of the crystal tower of each next stage is kept as low as this temperature difference.

According to the second process of the present invention, bisphenol A-phenol crystal adduct having high purity and good color can be obtained in high yield.

This bisphenol A phenol crystal adduct provides a bisphenol A of high purity and good color by separating and removing phenol from this.

(Third process)

Next, a third process for obtaining a crystal adduct according to the present invention will be described with reference to the drawings.

2 is an apparatus flow diagram for carrying out the third process of the invention. In this figure, (1) is an outer cylinder, (2) is an inner cylinder, (3) is a microcrystalline adduct dissolution tank, (4) is a cooler, (5) is a heater, (6), (7) is a pump, and A is Represents a crystal tower.

The crystal tower A has a double cylinder structure in which an inner cylinder 2 having an opening part is inserted into an outer cylinder 1 of a sealed structure.

The closed structure as used in the present invention refers to a state in which the crystal tower is sealed with an inert gas, rather than being in an open air state.

Opening the atmosphere will absorb some of the oxygen in the atmosphere in the slurry in the crystallization column, worsening the color of the adduct, and adversely affecting the subsequent treatment, so that high-quality adduct, even bisphenol A, cannot be obtained. . Therefore, in the crystal tower, it is necessary to seal with an inert gas in order to prevent the mixing of oxygen. In this case, if oxygen can be prevented from mixing, it is not necessarily a sealed pressure vessel that can withstand high pressure. In addition, the crystal tower does not need to provide a direct extraction hole in the outer cylinder portion, but installs the inner cylinder on the central axis of the swirl flow of the slurry inside and raises the swirl flow of the slurry to the upper portion thereof to make the slurry flow from the opening of the upper portion of the inner cylinder to open the inner cylinder. After descending, a method of ejecting from the inner cylinder bottom is taken. This makes it possible to ensure uniform mixing with respect to the circulating slurry introduced and sufficient residence time for the adduct particles.

In order to carry out the present invention preferably, first, a phenol solution containing bisphenol A as a raw material to be treated is filled into the crystallization tower A through lines 8 and 9, and at the same time from the bottom of the inner cylinder 2 with a line ( 10) extract the phenol solution through the line (11), pump (6), line (12), cooler (4), line (13) and line (9) continuously into the barrel of the bottom of the crystal tower A Circulate By this operation, the phenol solution in the crystal tower A is cooled to crystallize the crystal adduct and produce a slurry containing the crystal adduct. This slurry is taken out from the bottom of the inner cylinder 2, cooled in the cooler 4 as described above, and then circulated into the outer cylinder 1 at the bottom of the crystal tower A.

In addition, a portion of the slurry from the bottom of the inner cylinder 2 is transferred to the line 10, line 14, pump 7, line 15, heater 5, tank 3 and line 16, 17 Through the continuous circulation into the outer cylinder (1) of the lower portion of the crystal tower A through. By this operation, the microcrystalline adduct particles in the slurry extracted from the bottom of the inner cylinder 2 are dissolved in the tank 3, and the slurry having a low content of microcrystalline adduct particles is circulated into the crystal tower A. As a result, the content rate of the microcrystalline adduct particle in the crystallization tower A is reduced.

In this state, the raw material phenol solution is introduced into the outer cylinder 1 at the bottom of the crystal tower A through the lines 8 and 9, and at the same time the product slurry is removed from the bottom of the inner cylinder 2. Eject through)

In this case, if the slurry can be flowed down by gravity in the next step, it is extracted using the line 20 in this way. Otherwise, a part thereof may be extracted from the discharge line 21 of the pump 7. have. In addition, a part of the slurry having a small content of microcrystals may be recovered from the line 18, and this may be used as a product crystal adduct slurry.

In the present invention, when introducing the temperature-reduced slurry through the line (9) and the temperature-rise slurry through the lines (16) and (17) into the outer cylinder (1), the swirl flow in the same direction from the lower portion of the outer cylinder into the outer cylinder Introduce to create. In this case, Preferably it introduces so that it may become tangential with respect to an outer cylinder inner peripheral surface, and it introduces so that the introduction position may differ. If the introduction position is too close, the local flow may be disturbed and a flat swirl flow may not be obtained, and it is not preferable in terms of the structure and strength of the crystal tower. Therefore, the introduction positions of these two slurries are preferably displayed at an angle from the center point of the outer cylinder and preferably at a position separated by 90 to 180 degrees. And if it is for producing the swirl flow in the same direction, the introduction positions of the two slurries need not necessarily be on the same horizontal plane, and there may be some height difference at least under the outer cylinder.

As described above, each slurry flowing through the lines 9, 16 and 17 is introduced into the outer cylinder so that the swirl flow in the same direction is generated, and the swirl flow passes through the inside of the outer cylinder 1 (2). ) To the upper end of the inner cylinder 2, and then descends the inner cylinder 2 from the upper opening of the inner cylinder 2 and is discharged through the line 10 from the bottom of the inner cylinder.

By producing such a swirl flow in the outer cylinder 1, the following effects can be acquired.

(1) Two liquid streams of different temperatures can be effectively and uniformly mixed.

(2) Since dispersion of the slurry is prevented and the slurry concentration in the outer cylinder is uniform, nonuniformity of residence time in the outer cylinder of the crystal addition product particles can be eliminated.

(3) A sufficient linear velocity can be obtained to prevent sedimentation deposition in the outer cylinder of the crystal adduct particle.

In addition, as described above, a portion of the slurry extracted from the bottom of the inner cylinder 2 is transferred to the line 10, the line 14, the pump 7, the heater 5, the tank 3, and the lines 16 and 17. When circulating through the crystal tower A through the microcrystalline adduct in the slurry is dissolved and lost in the tank (3), a slurry containing a coarse crystal adduct of a certain size is circulated to the crystal tower A through lines (16) and (17). As a result, the grain size of the crystal adduct contained in the crystal tower A becomes uniform, and thus the crystal adduct is produced in the crystal tower A with a low content of microcrystalline adduct particles and a high content of coarse crystal adduct particles. The microcrystalline adduct in the crystal tower A has a large specific surface area and thus exhibits high adsorption to the coloring agent. Therefore, the crystal addition product of a good color can be obtained by reducing the content rate of the microcrystal addition product particle in the crystal addition product obtained by the crystal tower A as much as possible. According to the researches of the present inventors, it was found that high purity crystal adducts with good color can be produced by maintaining the content of microcrystalline adduct particles having a particle diameter of 100 μm or less in the crystal adducts at 30% by weight or less, preferably 20% by weight or less. It became.

The temperature of the phenol solution containing bisphenol A supplied from the line 8 is a temperature about 1-20 degreeC higher than the saturation temperature of an adduct, and the temperature of the crystallization tower A is 45-70 degreeC. The slurry circulated through the line 11, the pump 6, the cooler 4, and the line 9 is lowered in the cooler 4 at a temperature of about 10 ° C or less, preferably about 5 ° C or less. The residence time of the phenol solution in the crystal tower A is 0.5 to 10 hours, preferably 0.5 to 5 hours.

On the other hand, the slurry introduced into the microcrystalline adduct dissolution tank 3 through the line 14, the pump 7, the line 15, and the heater 5 has a temperature of 0.5 to 5 ° C. in the heater 5. It is raised to the extent that it is held in the microcrystalline dissolution tank 3. The residence time of the phenol solution in this tank 3 is about 3 to 15 minutes.

In the microcrystalline dissolution tank 3, a crystal adduct having a particle size of 100 μm or less is dissolved, and the content of the crystal adduct particle having a particle size of 100 μm or less in the crystal adduct in the slurry via the line 16 is 30% by weight or less, preferably 20 Weight% or less.

A part of the slurry drawn out from the bottom of the inner column 2 is recovered as a product slurry through the line 20. In this case, in the case of causing the slurry to flow down by gravity in the following process, it is extracted using the line 20 in this way. Otherwise, a part thereof may be extracted from the discharge line 21 of the pump 7. . In addition, a part of the slurry having a small content of microcrystals may be recovered from the line 18, and this may be used as a product crystal adduct slurry. This slurry can be subjected to the same crystallization treatment as above. In addition, the crystal addition product can be obtained by solid-liquid separation treatment of this slurry.

According to the third process of the present invention, it is possible to efficiently produce crystal adducts having a low content of microcrystalline adduct particles and good color. This crystalline adduct gives bisphenol A of good color by isolate | separating and removing a phenol from this.

(Fourth process)

Next, a fourth process for obtaining a crystal adduct according to the present invention and a crystallizing apparatus for carrying it out will be described with reference to FIG.

In FIG. 4, A is the first crystal tower, B is the second crystal tower, (3) to (4) is the first commercial cooler, (5) is the preliminary cooler, and (6) to (7) is A second commercial cooler is shown.

The phenol solution of bisphenol A which is a raw material is first introduced into the first crystal tower A from the line 101. A portion of the crystal adduct slurry drawn by the line 102 from the bottom of the first crystal tower A is passed through the pump 8 and the line 104 to the second crystal tower B, and a portion of the pump After cooling through (9) and (10) and coolers (3) and (4), it is returned from line 103 to the first crystal tower A. The temperature in the first crystallization tower A is determined according to the respective temperatures and inflow ratios of the raw material liquid flowing in from the line 101 and the circulating liquid flowing from the line 103, and the bisphenol is reached until a concentration corresponding to the temperature is reached. Precipitation of the crystal addition product which is equimolar between A and phenol occurs. The liquid flowing in the circulation line from line 102 through pumps 9 and 10 and coolers 3 and 4 to line 103 is thus a slurry comprising the crystal adduct. Similarly, a portion of the liquid drawn by line 105 from the bottom of the second crystal tower B is sent by line 107 to a filtration device for recovering the crystalline adduct, so that some of the pumps 12 and 13 And after cooling through the coolers 6 and 7, it is returned from the line 106 to the second crystal tower B. The temperature in the second crystal tower B is determined in accordance with the respective temperatures and inlet ratios of the liquid flowing in from the line 104 and the liquid flowing out of the line 106, and the bisphenol A and Precipitation of a crystal adduct that is equimolar with phenol occurs. The liquid flowing in the circulation line from line 105 through pumps 12 and 13 and coolers 6 and 7 to line 106 is therefore a slurry comprising the crystal adduct.

The line comprising the pump 11 and the cooler 5 is a spare line to take over the load when another pump and cooler is removed from the line. An example of the operation of the commercial coolers (3), (4), (6) and (7) and the preliminary cooler 5 is shown in Table 1 below.

Driving mode One 2 3 4 5 Cooler 3Cooler 4Cooler 5Cooler 6Cooler 7 AA / BB / AABB AAB / B A / ABB AABB /

In Table 1, A represents cooling the slurry of the first crystallization system, and B represents cooling the slurry of the second crystallization system. One cycle is completed at the time when the operation mode is sequentially shifted from (1) to (5) and returned to (1) again. In order to dissolve the crystal adduct deposited on the heat transfer surface, it takes about 1 hour after the liquid temperature in the cooler rises above the crystal dissolution temperature, but the heat transfer effect of the cooler decreases due to the attachment of the crystal adduct. The time until regeneration is required also depends on the conditions of use, but at least several ten hours and the cycle is easily achievable. In the fourth process of the present invention and the crystallizer for the implementation thereof, in the operation of the externally cooled crystallizer system which cools the crystal adduct slurry using the cooler as described above, the coolers are provided in parallel and the plurality of coolers are provided. One of the coolers is used as a preliminary cooler, and only the cooler other than the precooler is used to cool the crystal adduct slurry, and the cooler whose crystallization is deposited on the heat transfer surface and the heat transfer efficiency is reduced is replaced with the preliminary cooler. At the same time, it is characterized by dissolving and regenerating the crystal adduct attached to the heat transfer surface by heating the cooler whose heat transfer efficiency is lowered. In this case, one of the plurality of coolers may be fixedly operated as a preliminary cooler at all times, or may be operated cyclically with each cooler sequentially as a preliminary cooler.

The crystal tower in the present invention may be one, but preferably, as shown in FIG. 4, the crystal tower is installed in two towers in series to perform two-stage crystallization, and a commercial cooler is separately installed for each crystal tower. It is recommended to install one common cooler in both crystal towers. If the two-stage crystallization is carried out by installing two crystal towers in series, the difference between the inlet temperature of the crystalline adduct slurry in each tower and the temperature in the tower can be reduced, thereby avoiding the rapid crystallization, which leads to high purity. Large crystal adducts can be obtained. In addition, since the load on the cooler can be reduced, precipitation of crystals on the cooler heat transfer surface can be suppressed. And if the preliminary cooler is common to both towers, the installation cost can be reduced. In this case, the preliminary cooler alternately cools two kinds of liquids having different temperatures and solute concentrations. However, if the heat exchange capacity is the same, a slight difference in temperature or solute concentration is not a problem.

In the external cooling crystallizer system which cools the crystal addition product slurry using a cooler, the liquid flowing through the cooler is usually a slurry containing crystal (crystal addition product of bisphenol A and phenol). The cooler is a kind of indirect heat exchanger, and the slurry passing through the cooler is cooled through the heat transfer surface. Thereby, precipitation of a crystal advances to the extent corresponded to the temperature fall. However, there is a time lag between the temperature drop and crystal precipitation, and crystals gradually precipitate after being temporarily supersaturated. In addition, precipitation of crystal adducts requires the presence of seed crystals, and the precipitation proceeds in the form of crystals already existing in the slurry rather than new crystals because the crystals in the slurry act as seed seeds. Therefore, the rate at which the scale (consisting of fine crystals and impurities) is formed on the heat transfer surface of the cooler is not very large at first, but is accelerated gradually because it acts as a seed. When this scale accumulates, a problem arises that first, the heat transfer efficiency (ie, cooling efficiency) is lowered, and when the scale is peeled off and transported to the crystal tower, there is a problem that the purity of the product is lowered. Therefore, normally, when the scale accumulates, the cooler is removed from the line and cleaned. Since the operation of crystallization must be stopped during this operation, the operation of crystallization to some extent cannot be done frequently, and as a result, the cooler is used until a considerable scale has accumulated.

According to the invention the above problem is completely solved. That is, in the present invention, when fine crystals slightly precipitate on the cooler heat transfer surface without cleaning and removing the scale, the load of the cooler is switched to a preliminary cooler, and the cooler is allowed to flow a warming medium instead of a cooling medium, if necessary. It is to dissolve and remove fine crystals deposited on the heat surface. The heating medium may be separately provided with a circulation line, and the cooler may be connected to the heating medium circulation line. In this way, since fine crystals are removed before they form a hard scale, the scale attachment problem can be avoided by simply removing the cooler from the line and heating without the need for time-consuming and laborious scale cleaning operations. .

(5th process)

Next, a fifth process for obtaining a crystal adduct according to the present invention will be described with reference to the drawings.

5 shows an example of a flow sheet in the case of carrying out the method of the present invention. In FIG. 5, A-1, A-2, and A-3 represent a 1st crystallization process, a 1st crystallization process, and a 1st crystallization process, respectively. B-1, B-2, and B-3 represent a 1st solid-liquid separation process, a 2nd solid-liquid separation process, and a 3rd solid-liquid separation process, respectively. C-1 and C-2 represent the 1st remelting process and the 2nd remelting process of a crystal addition product, respectively.

In the case of producing the crystal adduct according to the flow sheet shown in Fig. 5, in the steady state flowchart, the phenol solution containing bisphenol A, which is the raw material for crystallization, is subjected to the first crystallization step A- via line (1). Introduced by 1.

The crystallization product obtained in the first crystallization step A-1 is introduced into the first solid-liquid separation step B-1 through line (2), where it is separated into the first crystal adduct D-1 and the first mother liquor F-1, Since 1st mother liquid F-1 contains useful components, such as a phenol and bisphenol A in it, after performing a suitable process, it circulates in the reaction process of a phenol and acetone. The first crystal adduct separated from the first crystallization product is washed with the second mother liquor F-2 obtained in the second solid-liquid separation step B-2 of the next stage, and the first washing liquid E-1 obtained in this washing is phenol. It is circulated in the reaction process with and acetone.

The first crystal adduct D-1 washed with the second mother liquor F-2 as described above is introduced into the first remelting step C-1 and the second crystal adduct from the second solid-liquid separation step B-2 in the next stage. It is dissolved by the washing drainage E-2 and then introduced into the second crystallization step A-2 via the line 3.

The crystallization product obtained in the second crystallization step A-2 is introduced into the second solid-liquid separation step B-2 through line 4, where it is separated into the second crystal adduct D-2 and the second mother liquor F-2. The second mother liquor F-2 is used to wash the crystal adduct D-1 separated in the first solid-liquid separation step B-1 as described above. On the other hand, the second crystal adduct D-2 is washed with the third mother liquor F-3 obtained in the third solid-liquid separation step B-3 of the next stage, and the second washing liquid E-2 is the first re-dissolution step as described above. It is used as a phenol solution for melt | dissolution of the 1st crystal addition product D-1 in C-1.

The first crystal adduct D-2 washed with the third mother liquor F-3 as described above is introduced into the second remelting step C-2, and the third crystal adduct from the third solid-liquid separation step B-3 in the next stage. After dissolving by washing | cleaning waste liquid E-3, it introduce | transduces into the 3rd crystallization process A-3 via the line 5.

The crystallization product obtained in the third crystallization step A-3 is introduced into the third solid-liquid separation step B-3 via line 6, where it is separated into the third crystal adduct D-3 and the third mother liquor F-3. The third mother liquor F-3 is used to clean the second crystal adduct D-2 separated in the second solid liquid separation step B-2 as described above.

The 3rd crystal addition product D-3 is wash | cleaned with refined phenol F, The 3rd washing | cleaning liquid E-3 dissolves the 2nd crystal addition product D-2 in a 2nd remelting process C-2 as mentioned above. Used as a phenolic solution.

The third crystal adduct D-3 washed with purified phenol F obtained in the third solid-liquid separation process is recovered as a product.

In the present invention, as the purified phenol F, usually, any one can be used as long as the molten color APHA is preferably 15 or less.

As the purified phenol that can be preferably used in the present invention, for example, various phenol purified products presented with respect to the purification method of the above crystal addition product can be used.

As the cleaning liquid of the crystal adduct of each step in the present invention, a mother liquid from the next stage is used for at least part thereof, but in this case, it is also possible to use a part of the cleaning liquid from the next stage in combination. As a phenol solution for dissolving the crystal adduct in each stage of re-dissolution, washing drainage from the next stage is used for at least part thereof, but in this case, a part of the mother liquor from the next stage is used in combination. You can do it. In the present invention, the cleaning liquid used for washing the crystal adduct and the phenol solution for dissolving the crystal adduct are both impurity concentrations contained in the downstream side, that is, from the crystallization step in the first stage to the crystallization step in the nth stage. It is being written down. In other words, the impurity concentration in the crystalline addition product washing liquid and the phenol solution for dissolving the crystalline adduct used in each stage is larger than that in the next stage. The impurity concentration in the washing liquid used in each adjacent stage decreases almost equipotentially.

In addition, an impurity as used in this specification means the side product at the time of producing bisphenol A by reaction of a phenol and acetone. Such impurities include isomers of bisphenol A, chroman compounds, and the like.

In addition, according to the required purity of the product adduct, a part of each washing process from the first stage to the n-1th stage is omitted, and the crystal addition product obtained in the solid-liquid separation process is directly brought to the next dissolution step. It may be. In this case, the phenol solution used in the remelting process uses the mother liquid (or washing liquid) obtained in the solid-liquid separation step of the next step.

As described above, in the present invention, the amount of the phenol used as a whole can be lowered and the cost can be reduced by adjusting the amount of the phenol solution for washing used in each stage according to the required purity of the product adduct.

Although the crystallization process in this invention is two or more stages, and the example which included the three-stage crystallization process was shown in the figure, even if it is four or more stages of crystallization processes, it can carry out similarly to the above.

According to the fifth process of the present invention, high-quality crystal adducts can be obtained only by using purified phenol only for washing the crystal adducts of the final stage. Therefore, in this invention, the use amount of high-purity refined phenol is at least, and there exists an advantage that the manufacturing cost of a crystal addition product may be low.

(The sixth process)

A sixth process for obtaining crystal adducts according to the present invention is described below. The crystal addition product slurry used as a raw material of this process is a crystal addition product slurry obtained by crystallizing a reaction product obtained by reacting phenol and acetone, or a crystal addition product obtained by crystallizing by re-dissolving the crystal addition product separated from this slurry. Water slurry and the like.

In the present invention, when the crystalline adduct slurry is filtered to separate the crystalline adduct from the mother liquor, at least a part of the microcrystalline adduct component having a particle size of 100 μm or less in the crystalline adduct contained in the slurry is transferred to the filtrate (mother liquor) side. A coarse crystal adduct having a proportion of the microcrystalline adduct component having a particle size of 100 µm or less is 20% by weight or less, preferably 15% by weight or less. In this case, in order to transfer the microcrystalline adduct component to the filtrate side, it can be performed according to the selection of a filter or selection of filtration operation conditions. Generally as a filter, the mesh is 100-150 micrometers, Preferably it is 100-125 micrometers. When the microcrystalline adduct component according to the filtration operation conditions is shifted to the filtrate side, it can be performed depending on the thickness of the crystal adduct cake obtained by the filtration treatment and the frequency of backwashing the cake.

In the present invention, the coarse crystal adduct obtained as described above is itself a high quality having a low impurity content, but the quality can be further improved by washing the coarse crystal adduct with purified phenol again. In this case, as the purified phenol, various phenol purified products presented with respect to the purification method of the above crystal adduct can be used.

The washing | cleaning of a crystal addition product with refined phenol should just be a method which can fully achieve contact of a crystal addition product with refined phenol. This washing treatment is a method of removing the mother liquor from the crystal adduct in a solid-liquid separation device such as a filter or centrifugal separator for separating the crystal adduct, and then introducing purified phenol into the solid-liquid separation device or washing the solid-liquid separation device. The crystal adduct attached by the small amount of mother liquor discharged | emitted from can also be wash | cleaned with refined phenol in a separate stirring tank. The use ratio of the purified phenol relative to the crystal adduct is 50 parts by weight or more, preferably 100 parts by weight or more based on 100 parts by weight of the crystal addition product.

The crystal addition product washed by the above-mentioned purified phenol is to attach purified phenol to the surface thereof, which is sent to the phenol removal process from the crystal addition product to remove the phenol from which the high-purity product bisphenol A is recovered. The removal of phenol from the crystalline adduct can be carried out by a conventionally known method such as distillation, extraction, steam stripping, or the like.

According to the present invention, it is possible to easily obtain a crystal adduct having excellent color stability and good thermal stability that is hardly colored. In addition, bisphenol A obtained by removing phenol from this crystal adduct is also a high-quality product which is excellent in color and hardly colored.

Next, each process for obtaining bisphenol A according to this invention is explained in full detail.

(First process)

The first process for obtaining bisphenol A according to the invention is described below.

In the present invention, the crystal adduct is used under substantially neutral conditions and has a melt color APHA of 15 or less, preferably 15 or less.

In the reaction between phenol and acetone for obtaining bisphenol A, strong acidic substances such as hydrochloric acid, sulfuric acid, and sulfonic acid type strong ion exchange resins are used as the acid catalyst. In addition to acting as a catalyst in the reaction system between phenol and acetone, such highly acidic substances also exhibit the action of promoting the generation of colored substances and impurities under heating conditions, thereby reducing the color and purity of the recovered bisphenol A and phenol. Therefore, it is proposed to remove or neutralize such strong acidic substances after the reaction so as not to flow to a subsequent dephenol process involving heating conditions. For example, in a reaction using hydrochloric acid as a catalyst, a method has been proposed in which a product is heated after the reaction to remove hydrochloric acid, and the remaining hydrochloric acid is neutralized with alkali to neutralize it to pH 5 to 6 (JP-A 47-43937). ). In addition, in the method using a strong acid type ion exchange resin, organic sulfonic acid is detached and mixed into the product by decomposition of the ion exchange resin when reacting, and thus a method of neutralizing the organic sulfonic acid using a weakly basic ion exchange resin is proposed. (US Pat. No. 4191843). On the other hand, since the color and purity of phenol and bisphenol A are lowered not only by acid but also by alkali, it is necessary to neutralize the strongly acidic substance by alkali so as not to exceed the neutralization point.

As described above, in the reaction in which phenol and acetone are reacted in the presence of a strong acidic substance, it is necessary to neutralize the strong acidic substance present in the reaction product so as not to cross the neutralization point or to remove it from the reaction system. When the alkali used for neutralization remains, it is necessary to remove this alkali. In addition, the removal of the strongly acidic substance or alkali present in the reaction product can be removed by using a multi-stage crystallization process in the subsequent crystallization process.

The term crystalline adduct under substantially neutral conditions used in the present invention means a crystalline adduct with the influence of the above strong acidic or alkaline substances removed. Such a crystal addition product is dissolved in an aqueous methanol solution adjusted to acidity so as to show pH 5.0, and in a pH measurement method under substantially non-isolating conditions of phenol, pH 4.90-5.50, preferably pH 4.95-5.20. Say that. In addition, pH of the crystal addition product shown in this specification is obtained from the said measuring method.

In the present invention, as the crystal adducts, those having substantially neutral conditions as described above are used, but in this case, it is preferable to keep the melt color APHA of the crystal adducts of 15 or less. Melt color APHA of 15 or less can be obtained by maintaining the crystal adduct under substantially neutral conditions as described above, but can be obtained by increasing the number of crystallization stages in the crystallization step as necessary, It can be obtained by washing water with purified phenol.

When the crystalline adduct is washed with purified phenol, the purified phenol may be any one as long as the content of impurities is small so as not to cause coloring of the product bisphenol A. In the present invention, as the purified phenol, the melt color APHA is usually 10 or less, preferably 5 or less.

As the refined phenol which can be preferably used in the present invention, various purified phenols described for the purification method of the above crystal adduct can be mentioned, for example.

The washing | cleaning of a crystal addition product with refined phenol should just be a method which can fully achieve contact of a crystal addition product with refined phenol. This washing treatment is a method of removing the mother liquor from the crystal addition product in a solid-liquid separation device such as a filter or centrifugal separator for separating the crystal addition product, and then introducing purified phenol into the solid-liquid separation device. The crystal adduct adhered by a small amount of mother liquor discharged | emitted from can also be wash | cleaned with refined phenol in another stirring tank. The use ratio of the purified phenol relative to the crystal adduct is 30 to 1000 parts by weight, preferably 100 to 300 parts by weight with respect to 100 parts by weight of the crystal adduct. The purified phenol after being used for washing the crystal adduct is used as it is or as a raw material phenol in the synthesis reaction step of bisphenol A after being used for washing the prepared crystal adduct obtained in the previous crystallization step.

In the present invention, the phenol is evaporated and removed from the melt obtained by heating and melting the crystal adduct. At this time, the oxygen concentration in the heating atmosphere in the heating melting step and the step of evaporating and removing the phenol from the melt is preferably 0.005 vol% or less. Preferably lower than 0.001 vol%.

The temperature at the time of heating and melting a crystal adduct is 115-180 degreeC, Preferably it is 120-150 degreeC, and the pressure is 1.0-5.0 atm in absolute pressure, Preferably it is 1.0- 1.9 atm. The heat melting of the crystal adduct may be accomplished using an external heating vessel.

Evaporation and removal of phenols from the melt of the crystalline adduct can be accomplished using distillation towers or thin film evaporators. In this case, the evaporation apparatus may be multi-stage, but the heating temperature of the final stage is 160-200 ° C., preferably 170-185 ° C., and the pressure is usually 100 Torr or less, preferably 5-40 Thor pressure is employed.

Preferred evaporation removal of this phenol is accomplished by distilling most of the phenol using a thin film evaporator or the like and then removing the remaining traces of phenol by steam stripping. In this case, the supply amount of steam is 1/50 to 1/5, preferably 1/25 to 1/10 by weight relative to bisphenol A.

The product bisphenol A obtained as described above has a purity of 99.95% by weight or more, and is excellent in color, and usually has a color of APHA 20 or less. Such high-quality bisphenol A is suitable as a raw material bisphenol A of high-quality polycarbonate or epoxy resin and also suitable as bisphenol A used in the optical field.

(Second process)

A second process for obtaining bisphenol A according to the present invention is described below.

The raw material for evaporation treatment used in this invention is a mixture containing the crystal addition product and aliphatic carboxylic acid whose melt-color AHPA is 15 or less in neutral conditions substantially.

In order to carry out the present invention preferably, the crystalline adduct or its melt or mixture of the crystalline adduct with phenol or its melt under substantially neutral conditions is melted in the presence of aliphatic carboxylic acid and heated under reduced pressure to give phenol. Evaporate off.

The aliphatic carboxylic acid used in the present invention exhibits an action of preventing the coloring of bisphenol A when the bisphenol A in a molten state is brought into contact with air for a long time or kept at a high temperature. In the present invention, bisphenol A having excellent color and no coloration can be obtained by evaporating a mixture composed of a crystal adduct and an aliphatic carboxylic acid under substantially neutral conditions, and evaporating off the phenol in the crystal adduct.

As aliphatic carboxylic acid, any thing may be used as long as it exhibits a coloring prevention effect with respect to bisphenol A, and a conventionally well-known thing is used. For example, formic acid, oxalic acid, citric acid, tartaric acid, glycolic acid, lactic acid, malic acid, glycerin acid and the like can be given. Such compounds decompose or isomerize at a temperature of 160 ° C. or higher during the reaction to show an excellent effect as a color inhibitor for bisphenyl A.

As the anti-coloring agent in the present invention, it is necessary to use aliphatic carboxylic acid. If oxalic acid ester, terephthalic acid, sodium hydrogen phosphate and the like are used, sufficient anti-coloring effect of bisphenol A cannot be obtained. Contact with air or at elevated temperatures causes bisphenol A to become pigmented, which significantly deteriorates its color. The addition amount of aliphatic carboxylic acid is 1-100 weight ppm with respect to a crystal addition product, Preferably it is 5-50 weight ppm.

In addition, in this invention, when melt | dissolving a crystal adduct or the mixture containing this in the presence of oxalic acid or citric acid, its melting temperature is 115-180 degreeC, Preferably it is 120-150 degreeC, and melting pressure is 1-5 atm. Preferably it is 1.0-1.9 atm. The molten atmosphere is preferably an atmosphere having a low oxygen concentration, and it is usually advantageous to use an atmosphere having an oxygen concentration of 0.005 vol%, preferably 0.001 vol% or less.

Furthermore, in the present invention, in order to melt a crystal adduct or a mixture containing the same in a short time, the crystal adduct or the mixture containing the same is diluted and melted using a heat phenol having almost no coloring such as purified phenol as described above. Or a method of dissolving a crystalline adduct or a mixture containing the same in a molten liquid solution.

In the present invention, the heated melt obtained as described above is evaporated. In this case, the evaporation is carried out under 130 to 200 deg. Preferred evaporation is performed such that the temperature of the entire melt is 185 ° C. or less and at least a portion of the melt is heated to a temperature of 160 ° C. or more. If the evaporation temperature is too low, the effect of the aliphatic carboxylic acid added as a coloring inhibitor cannot be sufficiently exhibited, while if too high, the color decomposition of the aliphatic carboxylic acid is caused. This evaporation process is carried out under reduced pressure and the pressure is 100 Torr or less, preferably 5 to 40 Torr. In addition, the atmosphere of the evaporation treatment is preferably an atmosphere having a low oxygen concentration, and it is generally advantageous to use an atmosphere having an oxygen concentration of 0.005 vol% or less, preferably 0.001 vol% or less.

According to the present invention, it is possible to obtain a product bisphenol A having high purity, excellent color, and prevention of coloring at the time of melting. Such a thing also has excellent storage stability.

(Third process)

A third process for obtaining bisphenol A according to the present invention is described below.

The crystal adduct of bisphenol A and phenol used in this invention is manufactured by a conventionally well-known method. That is, an excess of phenol and acetone can be reacted in the presence of a strong acid catalyst to obtain a reaction product containing bisphenol A, and then crystallized by the reaction product to obtain crystal adducts of bisphenol A and phenol. In this case, the purity of the crystal adduct can be improved by performing the crystallization process in multiple stages or by the method of washing the crystal adduct. However, in the case where a small amount of strongly acidic material used as a catalyst in the reaction between phenol and acetone is contained in the crystal adduct. There are many. This strongly acidic substance reacts with phenol or bisphenol A under heating conditions to promote the generation of colored substances and impurities, thereby lowering the purity of the recovered bisphenol A and phenol. On the other hand, strongly acidic substances used as catalysts in the reaction of phenol and acetone are generally removed by the neutralization treatment after the reaction and also by the multi-stage crystallization process, but the removal is often incomplete and usually in the crystal adduct. Trace amounts of strongly acidic material are incorporated.

The present invention uses, as a raw material, a crystal adduct containing a small amount of strong acid. The amount of the strongly acidic substance in the crystal adduct used in the present invention is usually 0.3 meq / L or less. Such a crystal adduct is dissolved in an aqueous methanol solution adjusted to acidity so as to show pH 5.0, and in a pH measuring method under substantially non-isolating conditions of phenol, pH 4.0 to 5.5, preferably pH 4.3 to 5.2. will be. As used herein, the term "crystal adduct" under weakly acidic conditions means a crystal adduct in such a pH range.

In the present invention, as the crystal adduct, it is used under mildly acidic conditions as described above. In this case, it is preferable to keep the molten color APHA of the crystal adduct below 15 or less. A crystal adduct with a melt color APHA of 15 or less can be obtained by increasing the number of crystallization stages in the crystallization step of crystallizing the crystal adduct, and also by washing the crystal adduct with purified phenol.

In order to carry out the present invention preferably, the crystalline adduct under mildly acidic conditions is melted in the presence of aliphatic carboxylate, and heated under reduced pressure to evaporate phenol off.

The aliphatic carboxylic acid salt used in the present invention reacts with the trace amount of strongly acidic substance incorporated into the crystal adduct, and neutralizes it and at the same time by-produces the aliphatic carboxylic acid liberated by the neutralization reaction. Therefore, in the present invention, when the crystal adduct is melted and evaporated in the presence of aliphatic carboxylate, there is no strong acidic substance that reacts with phenol and bisphenol A to generate coloring substance and impurities, thereby obtaining bisphenol A having excellent color. In addition, due to the anti-coloring effect of the by-product free carboxylic acid, the obtained bisphenol A is a thing that the coloring of the melt is significantly suppressed.

As the aliphatic carboxylate, any one can be used as long as it can react with a strongly acidic substance, but alkali metal salts, ammonium salts and alkaline earth metal salts are generally used. As the aliphatic carboxylic acid component of the aliphatic carboxylate, those having an anti-coloring effect on bisphenol A are preferably used, and conventionally known ones such as formic acid, oxalic acid, citric acid, tartaric acid, glycolic acid, lactic acid, malic acid, glycerin acid, and the like. Can be mentioned. These aliphatic carboxylates decompose or isomerize at a temperature of 160 ° C. or higher during the reaction, and exhibit an excellent effect as a color inhibitor for bisphenol A. The amount of aliphatic carboxylate added is the amount that substantially neutralizes the crystal adduct, that is, the amount of neutralization of the strongly acidic substance. The addition of more carboxylate salts than this neutralization equivalent is undesirable, and a large amount of carboxylate salts deteriorates the color of the product bisphenol A. When carboxylate is added, free carboxylic acid may be added together with the carboxylate when the amount of by-product free carboxylic acid is small and the coloring prevention effect by the free carboxylic acid is small. The addition amount of free carboxylic acid is 0.1-50 wt ppm with respect to a crystal addition product including by-product free carboxylic acid, Preferably it is 1-30 wt ppm. In the case of heating and melting the crystal adduct in the presence of a carboxylate salt, its melting temperature is 115 to 180 ° C, preferably 120 to 150 ° C, and the melting pressure is 1 to 5 atm, preferably 1.0 to 1.9 atm. . The molten atmosphere is preferably an atmosphere having a low oxygen concentration, and usually an atmosphere having an oxygen concentration of 0.005 vol% or less, preferably 0.001 vol% or less is advantageous. In the present invention, in order to melt the crystal adduct in a short time, the crystal adduct is diluted and melted using a heat phenol having almost no coloring such as purified phenol as described above, or the melting of the crystal adduct is completed. The method etc. which melt | dissolve in a liquid flow can also be employ | adopted.

In this invention, although the heating melt of the crystal addition product which added the aliphatic carboxylate was evaporated, the evaporation process in this case is performed under 130-200 degreeC and pressure reduction conditions. Preferred evaporation is carried out such that the temperature of the entire melt is 185 ° C. or less and at least a portion of the melt is subjected to heating at a temperature of 160 ° C. or more. If the evaporation temperature is too low, it will not be possible to sufficiently exhibit the anti-coloring effect of the by-produced aliphatic carboxylic acid in the reaction between the strongly acidic substance and the aliphatic carboxylate, while if too high, the color decomposition of the aliphatic carboxylic acid will be caused. This evaporation process is performed under reduced pressure, The pressure is 100 Torr or less, Preferably it is 5-40 Torr. In addition, the atmosphere of the evaporation treatment is preferably an atmosphere having a low oxygen concentration, and it is generally advantageous to use an atmosphere having an oxygen concentration of 0.005 vol% or less, preferably 0.001 vol% or less.

According to the present invention, it is possible to obtain a product bisphenol A having high purity and excellent color and preventing coloring at the time of melting. Such a thing also has excellent storage stability.

(Fourth process)

A fourth process for obtaining bisphenol A according to the present invention is described below.

As for the crystal addition product used in this invention, the melt color APHA is 15 or less, Preferably it is 10 or less. Such a crystal addition product can be obtained by multistage crystallization of the phenol solution containing bisphenol A. Furthermore, the crystal addition product obtained by crystallizing the phenol solution containing bisphenol A can be obtained by wash | cleaning with the refined phenol from which the said coloring cause substance was removed. Preferred crystal adducts for use in the present invention are those relating to the first, second and third processes of the present invention presented for obtaining bisphenol A.

The crystal adduct obtained as described above is treated with a phenol removal apparatus system from a crystal adduct including a melting apparatus and an evaporation apparatus, but in the present invention, at least the crystalline adduct is previously contained in the phenol removing apparatus. Oxygen removal treatment adhering to the surface of the material constituting the inner wall of the melting apparatus and the evaporation apparatus is performed.

The inner wall surface of the melting apparatus and the evaporation apparatus is formed of a metal material, usually stainless steel, such as SUS304, SUS 316, 316L, etc., and usually 30 to 60 millimoles of oxygen per 1 m ² is attached to the surface. . This oxygen amount can be measured by various methods. For example, there is also a method of obtaining and estimating the correlation between the cleaning conditions and the amount of surface-bonded oxygen measured by the surface etching by the test piece, but can also be measured from the relationship between the amount of surface-bonded oxygen and the coloring of the cleaning phenol. Also in the case of other cleaning liquids, the correlation between the coloring and the amount of surface-bonded oxygen can be determined in advance and used as a measuring method. For example, coloring of phenol becomes 6 APHA per 1 part by weight of oxygen, and can be used as a correlation of this measurement. According to the researches of the present inventors, when the melter and the evaporator are used by removing the oxygen adhering to the inner wall surface in advance, the melting agent and the evaporator are remarkably produced by the melting of the crystal adducts and the generation of the coloring causative material generated by heating in the evaporation of the melt. It was found that the product bisphenol having good color can be obtained by suppressing it.

Oxygen removal from the inner wall surface of the melting apparatus and the evaporation apparatus can be achieved by washing the inner wall surface with an organic solvent. As the organic solvent, phenol or bisphenol A, a mixture of phenol and bisphenol A, and the like can be used. The washing treatment temperature is 100 to 200 ° C, preferably 120 to 185 ° C. As the atmosphere for cleaning, a non-acidic gas atmosphere such as nitrogen gas, nitrogen gas, argon gas, or degassed gas, or a reduced pressure atmosphere is used, and the oxygen concentration in the atmosphere is 0.01 vol% or less, preferably 0.005 vol% or less. More preferably, it is 0.001 vol% or less. Cleaning of the inner wall by the organic solvent can be achieved by spraying the organic solvent on the inner wall through the spray nozzle. After washing with the organic solvent, the organic solvent remaining in the bottom of the melting apparatus and the evaporation apparatus is discharged, and the interior is dried as necessary. In addition, a trace oxygen analyzer by a conventional gas chromatography method or an electrochemical method can be used for the measurement of the concentration of the gaseous oxygen.

In the oxygen removal treatment from the inner wall surface, the amount of oxygen adhering to the inner wall surface is 10 millimoles or less, preferably 5 millimoles or less per 1 m ² of the inner wall surface.

As the melting apparatus, an external heating hermetic container having a heating jacket on the outer wall surface, or an internal heating hermetic container having a heating coil inside is used. Distillation column, stripping device, centrifugal thin film evaporator is used as the evaporator.

A pipe is provided between the melting apparatus and the evaporator, and a discharge pipe of bisphenol A is provided in the evaporator. In the present invention, the oxygen removal treatment is preferably performed on the inner wall surface of these pipes in the same manner as described above.

In the present invention, at least the melting apparatus and the evaporation apparatus included in the apparatus system as described above are subjected to the oxygen removing treatment of adhering to the inner wall surface thereof, and then the crystal additives are supplied to the apparatus system and the crystal addition is performed in the melting apparatus. Water is melted, and the obtained melt is evaporated by an evaporator to evaporate phenol.

The operating conditions of the melting apparatus are: temperature: 115 to 180 ° C, preferably 120 to 150 ° C, pressure: atmospheric pressure, oxygen concentration: 0.01 vol% or less, preferably 0.005 vol% or less, more preferably 0.001 vol% or less. Conditions are employed. The evaporator may be used in one stage or in multiple stages, but in the case of using in one stage, the operating conditions of the evaporator of the final stage in the case of using in one stage and in the case of multiple stages are 180 to 200 ° C, preferably Is 170 to 185 ° C, pressure: 1 to 100 Torr, preferably 5 to 40 Torr, oxygen concentration in the atmosphere: 0.005 vol% or less, preferably 0.001 vol% or less.

According to the present invention, it is possible to remarkably suppress the amount of the coloring causative agent due to the melting of the crystal adduct and the heating in the evaporation of the melt, thereby obtaining a high-purity bisphenol A having good color.

(5th process)

The fifth process for obtaining bisphenol A according to the present invention is described below.

As the crystal adduct used in the present invention, various crystal adducts presented with respect to the fourth process of the present invention presented for obtaining bisphenol A are used.

The crystalline adduct used as a raw material in the present invention is melted together with phenol attached to or entrained therein, and then led to an evaporation process comprising an evaporation tower in which a member for improving at least one evaporation surface area is disposed therein. In the present invention, the oxygen adhering to the inner wall surface of the evaporation tower and the surface of the member for improving the evaporation surface area is removed prior to the start of operation of the evaporation tower.

The inner wall of the evaporation tower and the member for improving the evaporation surface area, for example, the surface of the metal constituting the filler or the rack stage, are formed of conventional stainless steel, for example, SUS 304, SUS 316, SUS 316L, etc. About 30 to 60 millimolar of oxygen is attached and bonded per 1 m ² . According to the researches of the present inventors, when the evaporation tower is used by removing the oxygen adhering to the metal surface in advance, it is possible to remarkably suppress the generation of a coloring causative material caused by the heating in the evaporation treatment of the crystal adduct, and the color is good. It was also found that a product bisphenol A in which the change in color over time was suppressed can be obtained.

Oxygen removal from the inner wall surface of the evaporation tower and the surface which improved the evaporation surface area, for example, the filler surface, can be achieved by cleaning the surface with an organic solvent. As the organic solvent, phenol and / or bisphenol A, a mixture of phenol and bisphenol A, and the like can be used. Cleaning process temperature is 100-200 degreeC, Preferably it is 120-185 degreeC. As an atmosphere for washing, an atmosphere having an oxygen concentration of 0.1 vol% or less, preferably 0.05 vol% or less, such as an inert gas such as nitrogen gas, argon gas or degassing steam atmosphere is used. The cleaning of the inner wall surface of the evaporation tower and the surface of the member which improves the evaporation surface area by the organic solvent can be achieved by spraying a container solvent on the surface through a spray nozzle, and also by distributing the organic solvent into the evaporation tower.

In the oxygen removal treatment, the amount of oxygen adhering to the inner wall surface of the evaporation tower and the surface of the member for improving the evaporation surface area is 10 millimoles or less, preferably 5 millimoles or less per 1 m ² of surface area.

In the present invention, the oxygen removal treatment is applied not only to the inner wall surface of the evaporation tower and to the member surface for improving the evaporation surface area, but also to melt other metal surfaces such as crystal adducts contacted by the crystalline adduct melt or the bisphenol A melt. It is preferable to apply to the inner wall surface of the melting apparatus, the inner wall surface of the piping between the melting apparatus and the evaporation tower, and moreover, the inner wall surface of the bisphenol A extraction piping provided in the evaporation tower.

The crystal addition product in the present invention is heated and melted to form a molten liquid, and then supplied to an evaporation tower, whereby phenol is evaporated off.

As the melting apparatus of the crystal additive, an external heating hermetic container having a heating jacket on the outer wall surface, an internal heating hermetic container having a heating coil inside, or the like is used.

The operating conditions when melting the crystal adduct are generally temperatures: 115 to 180 ° C, preferably 120 to 150 ° C, pressure: 1.0 to 5.0 atm (absolute pressure), preferably 1.0 to 1.9 atm (absolute pressure) Conditions are employed. In addition, the oxygen concentration in the molten atmosphere of the crystal adduct is maintained at 0.005 vol% or less, preferably 0.001 vol% or less. In the present invention, in order to melt the crystal addition product in a short time, the crystal addition product is diluted or melted using a heat phenol having almost no coloring such as the above-described purified phenol, or the melting of the crystal addition product is finished. It is also possible to employ a method of melting in a liquid flow.

As an evaporation tower, the thing which provided the member which improves the evaporation surface area at least inside the cylinder body whose inner wall surface is formed from metal materials, especially stainless steel, for example, SUS304, SUS 316, SUS 316L, is used. This evaporation tower can provide heating means at its bottom. As a member for improving the evaporation surface area, a conventionally known filler, cache stage, wet wall, or the like can be proposed, and these can be used alone or in combination. In this case, it is composed of a filler, a cache end, a wet wall member material, a metal material such as stainless steel such as SUS 304, SUS 316, and SUS 316L. In addition, the filler may be a Raschig ring, a pall ring, a plate, or a perforated plate, and the tray of the cache stage may be a bubble type, a perforated plate, or the like. It may be with a down camem.

The evaporation tower is used in combination of at least one, preferably two or more. This evaporation tower may be an evaporation tower (vapor stripping evaporation tower) using steam. Preferred evaporation of the crystalline adduct melt according to the invention is achieved using a combination of a conventional evaporation tower without steam and a vapor stripping evaporation tower using steam.

Next, a method of evaporating a crystal addition product melt using an evaporation treatment system comprising a first evaporation tower using no steam and a first evaporation tower using steam will be described in detail.

In this evaporation treatment method, the molten liquid from the crystal addition product melting apparatus is introduced into the first evaporation tower and evaporated therein in the absence of steam and under reduced pressure, to evaporate a part of phenol in the melt. Steam containing phenol is separated and recovered from the top of the first evaporation tower, and a molten liquid in which part of the phenol is evaporated and removed is recovered from the bottom. The bottoms from the first evaporation tower are introduced into the second evaporation tower, where the evaporation is carried out in the presence of steam and under reduced pressure, and the residual phenol in the melt is evaporated off. From this second evaporation tower, a mixed vapor containing phenol, steam, and a small amount of bisphenol A is discharged from the tower top, and high-purity bisphenol A is separated and recovered as the column bottoms.

As operation conditions of the 1st evaporation tower which does not use steam, temperature: 125-200 degreeC, Preferably 130-185 degreeC, pressure: 100 Torr or less, Preferably 5-40 Torr is employ | adopted. The oxygen concentration in the vapor atmosphere in the evaporation tower is maintained at 0.005 vol% or less, preferably 0.001 vol% or less. In this first evaporation column, 95 to 99.8% by weight, preferably 98 to 99.7% by weight, of the phenol present in the crystal addition product melt is evaporated off.

The operating conditions of the second evaporation tower using the steam are: temperature: 130 to 200 ° C., preferably 160 to 185 ° C., pressure: 100 torr or less, preferably 5 to 40 torr, and steam supply amount per 1 kg of bisphenol A melt : 0.02-0.2Kg, Preferably the conditions of 0.04-0.1Kg are employ | adopted. The oxygen concentration in the vapor atmosphere in the evaporation tower is maintained at 0.005 vol% or less, preferably 0.001 vol% or less. In this second evaporation column, substantially the entire amount of phenol in the crystalline addition product melt obtained in the first evaporation column is evaporated off, and bisphenol A having a phenol content of 200 wt ppm or less, preferably 50 wt ppm or less is obtained as the bottoms. Lose.

A mixed vapor containing steam, phenol and a small amount of bisphenol A is obtained from the second evaporation tower using the above steam, but phenol and bisphenol A are separated and recovered from the mixed vapor. Separation and recovery of phenol and bisphenol A from this mixed steam can be carried out by various conventionally known methods, but in the present invention, in particular, by using a condensation method of stripping gas comprising a two-step cooling step described later, It is preferable to carry out.

According to the present invention, the evaporation treatment of the crystalline adduct melt can be carried out by using an evaporation tower having a large evaporation surface area under reduced pressure, so that the evaporation treatment can be carried out with good efficiency. Furthermore, in this case, as the evaporation tower, the amount of generation of colored causative substances due to heating in the evaporation of the melt can be obtained by using an oxygen removal treatment on the inner wall surface and the member surface disposed inside. High-purity bisphenol A can be obtained which can be remarkably reduced, excellent in color, and remarkably reduced the change in color of the melt over time.

(The sixth process)

The sixth process for obtaining bisphenol A by this invention is demonstrated below.

As the crystal adduct used in the present invention, various crystal adducts described in relation to the fourth process of the above invention indicated in order to obtain bisphenol A are used.

Next, a sixth process of the present invention will be described with reference to FIG.

In FIG. 6, (1), (2), and (3) represent a thin film evaporator. This is a structure of evaporating the thin film formed in the inner peripheral wall by heating from the outside. In the present invention, it is preferable to use a centrifugal thin film evaporator which has a rotary blade inside and which forms a liquid film on the inner peripheral wall surface in accordance with the rotation of the rotary blade.

In Fig. 6, reference numeral 4 denotes an external heater attached to each thin film evaporator. This is usually configured as a jacket through which the heating medium flows.

In this invention, the crystal addition product used as a raw material melt | dissolves this by heating or dilutes it with refined phenol, and makes it the phenol solution containing bisphenol A. The phenol solution preferably used in the present invention has a color of APHA 15 or less and a bisphenol A concentration of 50 to 80% by weight, preferably 60 to 75% by weight.

This raw phenol solution is introduced into the first thin film evaporator (hereinafter also referred to simply as the evaporator) 1 in line 10, and the phenol solution flows down the inner circumferential wall of the evaporator as a liquid film and the external heater therebetween. It is heated by (4) and discharged past the steam line 11 containing phenol and bisphenol A. This steam condenses this to recover phenol and bisphenol A.

The temperature of the phenol solution passing through the line 10 is preferably 120 to 150 ° C. The temperature of the 1st evaporator 1 is 160-185 degreeC, Preferably it is 165-175 degreeC, The pressure is 15-60 torr, Preferably it is 15-30 torr.

In the 1st evaporator 1, the residual liquid (bisphenol A) obtained by evaporating a raw material phenol solution is taken out through the line 12, and is introduce | transduced into the 2nd evaporator 2. As shown in FIG. The temperature of the evaporated balance of the phenol solution passing through the line 12 is preferably 170 to 185 ° C. Moreover, the phenol concentration in bisphenol A which comprises this balance is 1-5 weight%.

In the second evaporator (2), bisphenol A is heated by the external heater (4) while countercurrently contacting the stripping gas consisting of steam, phenol and bisphenol A extracted from the third evaporator (3), phenol, bisphenol The stripping gas containing A and steam is discharged past the line 13.

The temperature in the 2nd evaporator 2 becomes like this. Preferably it is 170-185 degreeC, and a pressure is 15 Torr or less, and usually 10-15 Torr.

The evaporation residue obtained in the second evaporator 2 is introduced into the third evaporator 3 via the line 14. Preferably the temperature of this residue is 170-185 degreeC, and the phenol concentration in bisphenol A which comprises a balance is 0.05-0.10 weight%, Preferably it is 0.05-0.07 weight%.

In the third evaporator 3, the bisphenol A from the second evaporator 2 is heated by the external heater 4 while in countercurrent contact with the steam introduced through the line 15, and the stripping gas is lined. Extracted after (17), this stripping gas is introduce | transduced into the 2nd evaporator 2 as the stripping gas. The temperature in a 3rd evaporator is 170-185 degreeC, and a pressure is 15 torr or less, and is usually 10-15 torr. The amount of steam introduced into the first evaporator 3 in the line 15 is 3% by weight or more, preferably 4 to 6, in weight ratio relative to the bisphenol A introduced into the third evaporator 3 through the line 14. Weight%. The composition of the stripping gas passing through the line 17 is phenol: 0.8 to 1.2% by weight, preferably 1% by weight or less, bisphenol A: 5 to 7% by weight, and the balance: steam.

The high purity bisphenol A obtained in the third evaporator 3 is extracted after the line 16. This bisphenol A has a phenol content of 0.005 wt%, and the color APHA has a high quality of 20 or less.

In the stripping gas discharged from the second evaporator 2 past the line 13, the phenol and bisphenol A contained in the gas are separated and recovered by using a condensation treatment. Although the stripping gas can be condensed by a conventionally known method, it is particularly preferable to carry out by using the condensation method of the stripping gas which consists of a two-step cooling process described later.

In the present invention, a phenol solution containing bisphenol A derived from bisphenol A-phenol crystal adduct is first evaporated using a first thin film evaporator to obtain bisphenol A having a phenol content of 1 to 5% by weight. In the case of the present invention, while the temperature of the first thin film evaporator is maintained at a condition of 160 to 185 ° C. and the pressure at 15 to 60 Torr, bisphenol A is not precipitated smoothly even if cooling due to rapid evaporation of phenol occurs. The evaporation process can be performed.

In the present invention, the bisphenol A obtained as described above is steam stripped by using a thin film evaporator in order to evaporate and remove the phenol contained therein. However, in the case of the present invention, the phenol content in the bisphenol A is 1 to 1. Since it is low as 5% by weight and two thin film evaporators are used in series, the temperature of these evaporators is maintained at 170 to 180 ° C. and is maintained at a high vacuum of 15 Torr or less to evaporate phenol in the bisphenol A. It is possible to obtain a high-purity bisphenol A with a phenol content of 0.005% by weight or less while being excellent in color.

In order to obtain bisphenol A which is excellent in color, the phenol solution containing bisphenol A which is the manufacturing raw material, and the temperature at the time of evaporating this solution are maintained at 185 degreeC or less, and generation | occurrence | production of colored impurities, such as isopropenyl phenol, is carried out. In the case of the present invention, since the evaporation temperature is maintained at 185 ° C. or lower, the phenol can be substantially completely evaporated and removed, and thus the bisphenol A obtained has a high purity with excellent color of APHA 20 or less. .

Moreover, in this invention, the phenol in a 2nd thin film evaporator is used by using the stripping gas which consists of the vapor | steam containing phenol and bisphenol A produced | generated by the 3rd thin film evaporator as a steam gas for stripping with respect to a 2nd thin film evaporator. There is also an advantage that the stripping effect is increased.

According to the evaporation treatment of the present invention, since the evaporation treatment can be performed in a very short residence time (usually 60 to 180 seconds) as a whole, the treatment efficiency is very high. In particular, in the case of the present invention, it is preferable to combine the first thin film evaporator, the second thin film evaporator, and the third thin film evaporator in order from the top, and to flow the liquid flow from the top to the bottom by gravity, and thus oxygen The leaf can be effectively prevented and the residence time of the liquid in the system can be kept short.

(Seventh process)

The seventh process for obtaining bisphenol A by this invention is demonstrated below.

As the crystal addition product to be used in the present invention, under the substantially neutral conditions indicated in relation to the first process of the present invention indicated to obtain bisphenol A, the melt color is 15 APHA or less, preferably 10 APHA or less Is used.

In the present invention, a solution containing bisphenol A, which is formed under crystal additives having a melt color of 15 APHA or less under substantially neutral conditions, is subjected to evaporation and removal of phenol under reduced pressure using a thin film evaporator under substantially anoxic. Process. In this case, substantially oxygen free means that the oxygen concentration in the atmosphere in the apparatus system for evaporating and removing phenol is 0.005 volume ppm or less. As a method of bringing the inside of the apparatus system into such an oxygen-free state, there is a method of purging an inert gas such as nitrogen gas or argon gas in the apparatus system, and more preferably, the step of depressurizing the inside of the apparatus system and under the reduced pressure. There is a method of repeatedly carrying out the step of purging the inert gas in the system.

In the case of evaporating off phenol from a solution containing bisphenol A formed from a specific crystal adduct according to the present invention, a coloring inhibitor may be added if necessary. This anti-coloring agent can be added directly to the crystalline adduct, in which case the anti-coloring agent is added and mixed to the crystalline adduct in any state, ie the crystalline adduct in powder, molten, slurry or solution state. You can.

In this invention, the coloring inhibitor which can be used preferably is an aliphatic carboxylic acid. This aliphatic carboxylic acid exhibits the effect of making bisphenol A in a molten state contact with the air for a long time or preventing coloring of bisphenol A when kept at a high temperature.

As aliphatic carboxylic acid, any thing can be used as long as it exhibits a coloring prevention effect with respect to bisphenol A, and a conventionally well-known thing is used. As such a thing, formic acid, oxalic acid, citric acid, tartaric acid, glycolic acid, lactic acid, malic acid, glycerin acid, etc. are mentioned, for example. These cause decomposition or isomerization at the temperature of 160 degreeC or more during reaction, and show the outstanding effect as a coloring inhibitor to bisphenol A. The addition amount of aliphatic carboxylic acid is 1-100 weight ppm with respect to a crystal addition product, Preferably it is 5-50 weight ppm.

By addition of this aliphatic carboxylic acid, the product bisphenol A with good thermal stability which prevented coloring at the time of melting can be obtained.

This invention can be implemented similarly to the case of the said 6th process of this invention using the apparatus system shown in FIG.

(Eighth process)

The eighth process for obtaining bisphenol A by this invention is shown below.

The stripping gas used as the raw material to be treated in the present invention is a gas obtained when stripping a mixture of phenol and bisphenol A with steam, and is composed of phenol, bisphenol A and steam. As such a stripping gas, for example, a stripping gas discharged from the line 13 shown in FIG. 6 can be used.

In the present invention, the stripping gas is supplied to the first cooling step as it is under reduced pressure, where it is cooled by making a countercurrent connection with a first cooling medium made of phenol or phenol containing bisphenol A. This first cooling step is performed such that substantially the entire amount of bisphenol A in the stripping gas is dissolved in the cooling medium. The vapor in the stripping gas is hardly condensed in this first cooling step, and is sent to the next first cooling step. Part of the phenol in the stripping gas is condensed in this second cooling process and the remaining uncondensed is sent to the next second cooling process with steam. A part of the mixed solution of bisphenol A and phenol separated and recovered from the stripping gas in the first cooling step can be used as a cooling medium. The temperature of a 1st cooling medium is a temperature about 1-50 degreeC higher than the freezing point of phenol. The recovery rate of phenol in this first cooling step is 70% by weight or more, preferably 85% by weight or more, relative to the pre-feed phenol for this first cooling step.

The cooling medium used in the first cooling step may be an amount sufficient to cool the stripping gas to a desired temperature, and is usually 5 to 10, preferably 5 to 6, by weight ratio to the stripping gas. The weight ratio of bisphenol A in the stripping gas obtained in the first cooling step to bisphenol A contained in the cooling medium in which the phenol is dissolved is 0.05 to 0.20, preferably 0.08 to 0.14. In the 1st cooling process, since excess phenol exists with respect to bisphenol A, even if it is cooling temperature below the freezing point of bisphenol A, the crystal adduct of bisphenol A and phenol does not crystallize.

The pressure of the first cooling process is 30 Torr or less, preferably 5 to 20 Torr and corresponds to the pressure in the second thin film evaporator 2. The temperature of the first cooling step is a temperature at which steam maintains a gas and a part of phenol maintains a liquid under the above pressure conditions. Preferable cooling temperature (temperature which condenses bisphenol A) is temperature which is 1-50 degreeC higher than the freezing point of a phenol, and its cooling temperature is 42-90 degreeC, Preferably it is 45-55 degreeC.

The mixed gas of steam and phenol sent to the second cooling step is cooled in countercurrent contact with a second cooling medium made of an aqueous solution of phenol. This 2nd cooling process is performed so that the substantially whole quantity of the vapor | steam and phenol sent to this process may be condensed, and in this process, the aqueous solution of phenol will be collect | recovered. The aqueous solution of the phenol obtained by this 2nd cooling process can use one part as a 2nd cooling medium. The concentration of phenol in the aqueous solution is determined by the composition of the stripping gas and the conditions of the first cooling step, but is usually 55 to 75% by weight. Moreover, the temperature of this 2nd cooling medium is a temperature about 1-10 degreeC lower than the steam condensation temperature.

The second cooling medium used in the second cooling step may be an amount sufficient to condense the total amount of the mixed gas, and is usually 100 to 300, in a weight ratio to the mixed gas of the vapor and the phenol sent in the first cooling step. Preferably it is 190-250. The pressure of this 2nd cooling process is 30 Torr or less, Preferably it is 5-20 Torr, and respond | corresponds to the pressure of a 1st cooling process. The cooling temperature (vapor condensation temperature) in the second cooling step may be a temperature at which the entire amount of the mixed gas of steam and phenol is condensed under the above pressure conditions.

The cooler used in a 1st cooling process and a 2nd cooling process should just be a gas-liquid contact type apparatus, and arbitrary things are used. As such a cooler, a packed tower, a spray tower, etc. can be used, for example. In the case of using a packed column, as the filler, it is preferable to use a Rashihi ring, a polling, a porous metal plate or the like so as to suppress pressure loss. In addition, although the coolers used by a 1st cooling process and a 2nd cooling process may be respectively provided separately, the 1 tower type apparatus containing two coolers may be sufficient.

Next, an embodiment of the above condensation treatment method for stripping gas will be described with reference to the drawings.

In Fig. 7, reference numeral 21 denotes the first cooler and reference numeral 22 denotes the second cooler. Line 23 indicates a stripping gas line connected to the line 13 shown in FIG. Line 24 is a vacuum line that connects to an exhaust pump (not shown) and a cooler, and the entire electric system including the cooler is maintained under reduced pressure.

The stripping gas is fed to the lower part of the first cooler 21 via line 23, where it is introduced into the first cooling medium (phenol or bisphenol A) at the top of the first cooler beyond line 25. Phenol)) in countercurrent contact. The cooling medium which melt | dissolved bisphenol A and phenol which condensed in this 1st cooler is taken out at the bottom of a 1st cooler through the line 26 containing the extraction pump 27. As shown in FIG. The cooling medium discharged past this line 26 may be partially recycled to the line 25 as a cooling medium after cooling a part of it to the required temperature if necessary.

The mixed gas of steam and phenol which is extracted from the top of the first cooler 21 via the line 28 is introduced into the lower part of the second cooler 22, where the upper part of the second cooler is past the line 29. In countercurrent contact with a second cooling medium (aqueous solution of phenol) introduced at In this second cooler, the mixed gas of steam and phenol is condensed, and this condensate is drawn off at the bottom of the second cooler 22 together with the cooling medium and past the line 30 including the pump 31 and Some pass over line 33, cool down past cooler 34 for the cooling medium, then pass over line 29 and are recycled to the second cooler. The remainder of the cooling medium containing condensed vapor and phenol extracted via line 30 is drawn out of system beyond line 32.

Next, in the condensation treatment method of the stripping gas, a flow sheet in the case of using a first tower cooling device including a first cooler and a second cooler is shown in FIG.

In Fig. 8, reference numeral 50 denotes a tower cooling device having a first cooler 21 and a second cooler 22 therein. This cooling device has a structure in which a partition plate 45 having an opening in the center is disposed in the middle of the first cooler 21 and the second cooler 22, and the tubular body 43 is formed in the opening. Have In this apparatus, the annular hollow chamber formed between the outer circumferential surface of the cylinder body 43 and the inner wall of the cooling device 50 is for storing liquid. Reference numeral 42 is a guide plate for guiding the liquid flowing down the second cooler 22 to the annular hollow chamber. Normal space 44 represents a gas passage.

In addition, in the code | symbol of FIG. 8, the same code | symbol as shown in FIG. 7 shows the same meaning. 8, the flow control system shown in FIG. 7 is not shown.

According to the condensation treatment of the stripping gas, the stripping gas can be cooled under a reduced pressure of 30 Torr or less without boosting the stripping gas. Moreover, in this case, despite adopting a low pressure condition of 30 torr or less and thus a low steam condensation temperature condition, crystals of bisphenol A or phenol are not precipitated at all. Therefore, in the condensation treatment method of the stripping gas, the efficiency of the cooler due to solid precipitation and the problem of closing the cooler do not occur at all.

Further, according to the condensation treatment of the stripping gas, all of steam, phenol and bisphenol A constituting the stripping gas are condensed, and their gas is not substantially introduced into the vacuum exhaust machine. Therefore, the vacuum exhaust pump is advantageous because only the apparatus system is maintained at a predetermined decompression condition, the exhaust capacity is small, and the equipment cost and energy cost are small.

Example

Next, the present invention will be described in more detail with reference to Examples.

A: Purification Method of Crystal Additives

Example A-1

Commercially available industrial phenols (moisture concentration 0.1 wt%, impurity concentration 0.05 wt%) were contact-treated using a Amberlite IR-118H + resin manufactured by Rohm and Haas at a temperature of 80 ° C. and a contact time of 50 minutes, and a distillation column temperature of 175 It distilled at 560 torr of column top pressure, and the refined phenol of melt color 6 APHA was obtained.

On the other hand, a mixture of bisphenol A, phenol, and impurities, which are molten color 50 APHA obtained by reacting phenol and acetone in the presence of an acid catalyst, was crystallized to precipitate a crystal adduct.

Next, the slurry of this crystal adduct was filtered under reduced pressure to obtain a solid crystal adduct, and the resultant was washed using the purified phenol obtained above at a ratio of 2.5 parts by weight based on 1 part by weight of the crystal adduct. Thus obtained crystal adduct was steam stripped at 175 ° C. and 25 Torr for 30 minutes to substantially completely remove phenol to obtain bisphenol A. This bisphenol A had a melt color (APHA) of 15 and an extremely good color. The melt color (APHA) number is ASTM. It was measured according to D 1686 (Standard Test Method for Color of Solid Aromatic Hydrocarbons and Related Materials in the Molten State).

Comparative Example A-1

A mixture of bisphenol A, a phenol and an impurity of melt color 50 APHA was crystallized to precipitate a crystal adduct. The slurry of this crystal addition product was filtered under reduced pressure, the solid crystal addition product was obtained, the one part was decomposed | disassembled at 190 degreeC, and phenol was collect | recovered. This phenol was wash | cleaned using the ratio of 2.5 weight part with respect to 1 weight part of remaining crystal adducts. The washing crystal adduct thus obtained was steam stripped at 175 ° C. and 25 Torr for 30 minutes to substantially remove all of the phenol to obtain bisphenol A, but this was a melt color of 20 APHA. Moreover, the color when this bisphenol A was kept at atmospheric pressure for 5 hours after melting was 80 APHA.

Comparative Example A-2

When distilling purified phenol, the distillation column bottom temperature was 200 degreeC and it carried out similarly to Example A-1, and obtained phenol. Bisphenol A was obtained in the same manner as in Example A-1 using this phenol as a washing liquid for crystal adduct, but this was a melt color of 30 APHA.

The molten color at 175 degreeC of the bisphenol A obtained by said Example A-1 and Comparative Examples A-1 and A-2 is put together in the following table, and is displayed.

TABLE A-1

number Melt Color of Bisphenol A (APHA) Example A-1 15 Comparative Example A-1 20 Comparative Example A-2 30

Example A-2

Industrial phenols having a water concentration of 0.07 wt% and an impurity concentration of 430 wt ppm were subjected to contact treatment at a temperature of 80 ° C. and a contact time of 20 minutes using Amberlite IR-118H + resin manufactured by Rohm and Haas. Next, the obtained contact treated material was distilled at the distillation column bottom temperature of 173 degreeC, and column top pressure 560 Torr, and the refined phenol was obtained.

Comparative Example A-3

The experiment was carried out in the same manner as in Example A-2, except that industrial phenol having a water concentration of 0.73 wt% and an impurity concentration of 430 wt ppm was used.

The properties of the purified phenol obtained as described above are shown in Table A-2 together with the properties of the raw material industrial phenol and the phenol after ion exchange resin treatment.

Table A-2

number Item Raw material for industrial phenol Phenolic After Ion Exchange Resin Phenolic After Distillation Example A-2 Impurity color 430 wt ppm (310 wt ppm) 20 APHA 1205 wt ppm (not detected) 30 APHA 5 wt ppm (undetected) 5 APHA Comparative Example A-3 Impurities (Benzofuran) Color 430 wt ppm (310 wt ppm) 20 APHA 796 wt ppm (42 wt ppm) 30 APHA 115 wt ppm (25 wt ppm) 10 APHA

Example A-3

Although the ion exchange resin treatment shown in Example A-2 was continuously performed for 1000 hours, in this case, benzofuran, which is a compound representing impurities, was not detected in the phenol after the treatment.

Example A-4

After reacting phenol and acetone in the presence of an acid catalyst, bisphenol A, a molten color 50 APHA obtained by evaporating most of the produced water and a part of phenol from the reaction product obtained, is crystallized by crystallization. Precipitated. The crystalline adduct slurry solution was filtered under reduced pressure, and the purified phenol obtained by the method described below was washed using 2.5 parts by weight based on 1 part by weight of the adduct. Thus obtained crystal adduct was steam stripped at 175 ° C. and 25 Torr for 30 minutes to substantially completely remove phenol to obtain bisphenol A. The molten color of this bisphenol A was 10-15 APHA, and the color was extremely good. Moreover, when the bisphenol A was kept at atmospheric pressure for 5 hours after melting, it was confirmed that the color was 30 APHA, and the colorability was low.

In addition, the purified phenol used above is a thing of melt color 5 APHA, This is the thing which dehydrated the phenol which evaporated and separated the said phenol from the reaction product with acetone (water concentration 0.1 wt%), rom and Haas Corporation make. It was obtained by contact treatment with an Amberlite IR-118H + resin at a temperature of 80 ° C. and a contact time of 50 minutes, followed by distillation at a column bottom temperature of 175 ° C. and a tower static pressure of 560 Torr.

B: Method of Producing Crystal Additives

Example B-1 (second process)

According to the apparatus flow diagram shown in FIG. 2, in the phenol solution containing bisphenol A, the slurry containing crystal addition product was obtained, and the crystal addition product was collect | recovered separately from this slurry. The relationship with the line or apparatus which indicated the main operation conditions in this case by the code | symbol in FIG. 2 is shown below.

(1) Composition of Ingredients in Feedstock in Line (1)

Bisphenol A: 22% by weight

Phenolic: 74 wt%

Other: 4 wt%

(2) Crystal Tower A

(i) Temperature: 54 ℃

(ii) Residence time: 120 minutes

(3) Melt tank of microadducts attached to crystal tower A

(i) Temperature: 55 ℃

(ii) Residence time: 6 minutes

(4) crystal tower B

(i) Temperature: 47 ℃

(ii) Residence time: 120 minutes

(5) The microcrystalline adduct dissolution tank attached to the crystallization tower B

(i) Temperature: 48 ℃

(ii) residence time: 6 minutes

In the above experiment, the content of the fine particle component having a particle size of 100 µm or less in 15 APHA and the crystal adduct was 13 weight% in the color of the crystal adduct separated from the slurry obtained through the line 35.

Comparative Example B-1

In the apparatus system shown in FIG. 2, the crystalline adduct slurry was manufactured using only the crystal tower A of the 1st stage. In this case, the operating conditions of the crystallization tower A were the same as in the case of Example B-1 except that the temperature was 47 ° C and the temperature of the microcrystalline adduct dissolution tank Q placed in the crystallization tower A was 48 ° C. .

The color of the crystal addition product obtained by this experiment was 30 APHA, and the ratio of the microparticle component of 100 micrometers or less in particle size in the crystal addition product was 29 weight%.

Example B-2 (third process)

According to the apparatus flow diagram shown in FIG. 3, the slurry containing a crystal addition product was obtained from the phenol solution containing bisphenol A, and the crystal addition product was collect | recovered and recovered from this slurry. In Fig. 3, the main operation conditions in this case are shown below in relation to the line indicated by the reference sign or the device.

(1) Composition of Feedstock in Line (8)

Bisphenol A: 22% by weight

Phenolic: 74 wt%

Other: 4 wt%

(2) Crystal Tower A

(i) Temperature: 54 ℃

(ii) Residence time: 120 minutes

(3) Melt tank of microcrystalline adducts attached to crystal tower A (3)

(i) Temperature: 55 ℃

(ii) Residence time: 6 minutes

In the above experiment, the proportion of the particles having a particle size of 100 μm or less in the crystal adduct separated from the slurry obtained via the line 20 was 20% by weight.

Example B-3 (third process)

In Example B-2, the temperature of the crystallization tower A is changed to 44 ° C, and the difference between the temperature in the microcrystalline adduct dissolution tank 3 and the temperature of the crystallization tower A is set to 5 ° C, and again The experiment was performed similarly except having set the residence time of the slurry in the tank 3 to 4 minutes. As a result, the proportion of the particulate component having a particle size of 100 µm or less contained in the crystal adduct in the slurry recovered through the line 20 was 29.5 wt%.

Comparative Example B-2

In Example B-3, the same experiment was conducted except that a part of the slurry extracted from the bottom of the inner cylinder 2 was not recycled through the heater 5 and the tank 3. As a result, the proportion of the particulate component contained in the crystal adduct in the slurry recovered through the line 20 was 69% by weight.

Reference Example B-1 (Reference Example of the 5th Process)

The reaction product obtained by making acetone and phenol react in presence of an acidic catalyst was concentrated, crystallized at 50 degreeC, and 3000 g of crystallization slurries of 20 wt% of bisphenol A phenol addition products were obtained. The resultant was filtered under reduced pressure at 50 ° C (preparation of the mother liquor (2250 g) after filtration obtained as A) using 600 g of purified phenol prepared separately, and 580 g of the washing liquid obtained at that time was B. ).

The crystalline adduct after washing was redissolved in 1310 g of purified phenol (APHA: 5) separately prepared, crystallized at 50 ° C, and a slurry of 20 wt% of bisphenol A-phenol adduct was obtained, which was filtered under reduced pressure at 50 ° C ( At this time, 1430 g of the obtained mother liquor was taken as C), and filtration was performed twice with 600 g of purified phenol separately prepared (the first washing drainage 580 g obtained at this time was D, and 580 g of the second washing drainage was E). ). Bisphenol thus obtained ^. The impurity concentration of the phenol crystal adduct was 100 wt ppm and the molten color was 5 APHA.

Example B-4 (Fifth Process)

In the same manner as in Reference Example B-1, the reaction product obtained by reacting acetone and phenol in the presence of an acid catalyst was concentrated and crystallized at a temperature of 50 ° C to obtain 3000 g of a crystallization slurry of bisphenol A and 20 wt% of a phenol crystal adduct. The crystal adduct obtained by filtering this under reduced pressure at 50 degreeC was wash | cleaned with the mother liquor C of Reference Example B-1. Additional crystals after washing refer to water added to the remaining 730 g and washed drain D 580 g of stock solution C of Example B-1, after the re-dissolution, crystallization from 50 ℃, and ^bisphenol-A. The crystallization slurry of 20 wt% of phenol crystal adducts was obtained, and the resultant was filtered under reduced pressure at 50 ° C. Subsequently, the obtained crystal adduct was washed with 580 g of washing liquid E in Reference Example B-1, and then washed with 600 g of purified phenol again as a final washing step. Bisphenol A obtained at this time ^. The impurity concentration of the phenol crystal adduct was 100 wt ppm as in the reference example, and the melt color was 5APHA.

Therefore, in this Example, only the refined phenol was used for the washing | cleaning process of the last stage, and all the rest used the mother liquid or washing | cleaning liquid collect | recovered at the back-end side of a process, and the usage-amount of refined phenol is reduced, and high quality bisphenol is used. A-phenol crystal adduct, Furthermore, high quality bisphenol A can be obtained.

Example B-5 (sixth process)

In the reaction product obtained by making phenol and acetone react in presence of an acidic catalyst, after distilling a phenol, the obtained concentrate is crystallized at 50 degreeC, and bisphenol A. is carried out ^. A crystal adduct slurry containing 20 wt% phenol crystal adduct was obtained.

Next, the slurry was filtered under reduced pressure while maintaining a slurry temperature at 50 degreeC with the filter which set the filter cloth which has a 106 micrometers mesh, and the obtained crystal addition product cake was wash | cleaned with refined phenol.

The proportion of the microcrystalline adduct component of 100 µm or less in this washing crystal addition product was 5% by weight. The molten color of this crystal adduct was 10 APHA, and the concentration of colored impurities was remarkably low. Moreover, the density | concentration of the chromman compound (colorable impurity) contained in this crystal adduct was 100 wt ppm.

Moreover, except having used the thing of the various mesh as a filter cloth in the above, the crystal adduct which variously changed the microcrystal addition product content rate of particle size 100 micrometers or less was obtained. About this crystalline adduct, the density | concentration of the hue APHA of a molten color, and a Kroman compound is measured, and the result is shown to Table B-2.

Table B-2

Experiment number Percentage of microcrystalline adduct component (% by weight) Crystalline adduct Color (APHA) Chromman Compound Concentration (wt ppm) 1 2 3 4 5 510203545 1015203040 100110150230400

As can be seen from the results shown in Table B-2, the crystal adduct having a proportion of the microcrystalline adduct component having a particle size of 100 μm or less and 20% by weight or less is excellent in color and has a concentration of a chroman compound which is a coloring impurity. It is of low quality.

C: Preparation of Bisphenol A

Example C-1 (First Process)

A mixture of bisphenol A, phenol and impurities, obtained by reacting phenol and acetone in the presence of an acid catalyst, was treated in a multistage crystallization process to obtain a crystalline adduct of molten color APHA 5, pH 5.05.

Next, the crystalline adduct was heated and melted using an external heat-sealing heating vessel under conditions of temperature: 130 ° C., pressure (absolute pressure): 1.20 atm, and atmospheric oxygen concentration: 0.0010 vol%. To a closed evaporator, and evaporated at a melt temperature of 180 ° C. and an oxygen concentration of 0.001 vol% in the atmosphere, and then steam was introduced, and at a temperature of 180 ° C. under an oxygen concentration of 0.0030 wt%. Stripped.

The bisphenol A thus obtained had a purity of 99.96% by weight or more and a prephenol content of 30 wt ppm or less, and was of a high quality exhibiting the color of the molten color APHA 20.

Comparative Example C-1

In Example C-1, experiments were conducted in the same manner except that the oxygen concentration in the atmosphere in the heating and melting step of the crystal addition product and the evaporation and stripping treatment step of the melt were set to 0.006 vol%. In this case, the obtained bisphenol A exhibited a molten color APHA 65 and had a purity of 99.96% by weight or more and a prephenol content of 30 wt ppm or less.

Comparative Example C-2

In Example C-1, the same experiment was conducted except that the separately prepared molten color APHA 10 and pH 4.85 crystal addition product were used. In this case, the obtained bisphenol A exhibited a fused color APHA 40, and had a purity of 99.90% by weight or more and a free phenol content of 50 ppm or less.

Comparative Example C-3

In Example C-1, the same experiment was conducted except that the separately prepared molten color APHA 20 and pH 5.05 adduct were used. Obtained bisphenol A showed the molten color APHA45, and was 99.96 weight% or more in purity, and 30 wt ppm or less of prephenol content.

Example C-2

In Example C-1, the experiment was carried out in the same manner except that the oxygen concentration in the atmosphere in the heat melting step of the crystal addition product and the evaporation treatment step of the melt were variously changed. The results are shown in Table C-1.

In addition, BPA in Table C-1 represents bisphenol A. Experiment number 6 shows a comparative example.

TABLE C-1

Experiment number Oxygen concentration in the atmosphere (vol%) Product BPA Crystal Additive Melting Process Evaporation process Steam stripping process Color of BPA (APHA) Free Phenolic (wt ppm) in BPA Purity of BPA (wt%) One 0.0001 Left 0.0002 10 <30 ＞ 99.96 2 0.0005 Left 0.0010 10 <30 ＞ 99.96 3 0.0015 Left 0.0040 25 <30 ＞ 99.96 4 0.0020 Left 0.0040 30 <30 ＞ 99.96 5 0.002 Left 0.0045 30 <30 ＞ 99.96 6 0.0030 Left 0.0055 40 <30 ＞ 99.96

Example C-3 (second process)

A mixture of bisphenol A, phenol and impurity, which is a molten color 50 APHA, obtained by reacting phenol and acetone in the presence of an acid catalyst, was crystallized in multiple steps to precipitate a crystal adduct. The slurry solution was filtered under reduced pressure to obtain a solid crystal adduct, and the purified phenol obtained by the method described later was washed at a ratio of 2.5 parts by weight based on 1 part by weight of the adduct. 10 ppm by weight of the additive shown in Table C-2 was added to the crystal adduct obtained as described above (color: APHA 5 to 10, pH 5.05 or less), and melted under the conditions of temperature: 150 ° C and oxygen concentration in the atmosphere: 0.0010 vol%. Subsequently, the obtained melt was evaporated under the conditions of temperature: 175 ° C., pressure: 10 Torr, oxygen concentration in the atmosphere: 0.0010 vol%, and phenol was substantially completely removed to obtain bisphenol A. In this case, the prephenol content was 30 wt ppm or less.

Next, the bisphenol A was heated and maintained at 175 ° C. for 0 hours or 2 hours under an air atmosphere, and the accelerated thermal stability test (test B) was carried out by blowing air at 175 ° C. for 2.0 hours. Evaluated the color at that time. The results are shown in Table C-2. In addition, experiment numbers 6-12 show a comparative example.

Table C-2

In addition, the refined phenol used above was of melt color 6 APHA, and commercial phenol (water concentration of 0.1 wt%, impurity concentration of 0.05 wt%) was used at 80 ° C, using Amberlite IR-118H + resin manufactured by Rohm and Haas. It was obtained by contact treatment at a contact time of 50 minutes and by distillation at a distillation column bottom temperature of 175 ° C and a tower static pressure of 560 Torr.

Comparative Example C-4

In Example C-3, the same experiment was conducted except that the separately prepared molten color APHA 5 to 10 and pH 4.85 crystalline adduct were used. The color of Bisphenol A obtained in this case was as Table C-3. Moreover, the prephenol in bisphenol A was 50 wt ppm.

Table C-3

Comparative Example C-5

Bisphenol A was obtained in the same manner as in Example C-3 when the purified phenol was distilled off at a column bottom temperature of 200 ° C., but this showed a molten color APHA 30 after Test A of 175 ° C. to 0 hours.

Example C-4 (Third Process)

A mixture of bisphenol A, a phenol and an impurity, which is a molten color 50 APHA, obtained by reacting phenol and acetone in the presence of an acid catalyst, was crystallized in multiple steps to obtain a crystal addition product (color: APHA 5-10, pH 4.85 or less). The additive shown in Table C-4 was added to this crystal addition product, and the resultant melt was melted under the conditions of temperature: 150 ° C. and oxygen concentration in the atmosphere: 0.0010 vol%. The resulting melt was then heated to temperature: 175 ° C., pressure: 10 torr, and atmosphere. Medium oxygen concentration: It was evaporated under the conditions of 0.0010 vol%, and phenol was substantially completely removed to obtain bisphenol A. In this case, the prephenol content was 30 wt ppm or less.

Next, the thermal stability test (test A) which hold | maintains this bisphenol A for 0 hours at 175 degreeC, and 2 hours at 175 degreeC under air atmosphere, and the accelerated thermal stability test (test B) which blows air at 175 degreeC for 2.5 hours are performed next. The color at that time was evaluated. The results are shown in Table C-4. In addition, experiment numbers 6-9 show a comparative example.

In addition, in the additive shown in Table C-4, the addition amount of the additive (Experiment Nos. 1 to 5) according to the present invention is the neutralization equivalent amount of the strongly acidic substance in the crystal addition product (about 1 ppm relative to the crystal addition product), for comparison. The amount of the additive (experimental numbers 6 to 8) added is about 20 ppm relative to the crystal adduct.

Table C-4

Example C-5

In Example C-4, the same experiment was conducted except that the molten color APHA 5 to 10 and pH 4.22 crystal addition product were used. The results are shown in Table C-5.

In addition, in the additive shown in Table C-5, the addition amount of magnesium citrate and sodium malate according to the present invention is a neutralization equivalent amount (about 4 ppm relative to the crystal addition product) of the strongly acidic substance in the crystal addition product. The addition amount of citric acid used for this is 20 ppm with respect to a crystal addition product.

Table C-5

Example C-6 (fourth process)

As the melting apparatus, an external heating hermetic container made of SUS 304 was used, and a stripping apparatus made of SUS 304 was used as the evaporator. The crystal addition product supply pipe was provided in the upper part of the melter, and the melt pipe was provided in the bottom part, and this melt pipe was connected to the middle part of the stripping apparatus. In addition, a pipe for phenol vapor discharge was provided at the top of the stripping device, and a pipe for discharging the melt of bisphenol A was provided at the bottom thereof. In addition, all of the said piping was made of SUS304.

Next, in the apparatus system configured as described above, the inner wall surface of the melting apparatus, the inner wall surface of the stripping apparatus, the piping between the melting apparatus and the stripping apparatus, and the liquid of bisphenol A melt attached to the stripping apparatus. The inner wall surface of the piping for discharging of was cleaned as follows.

(1) Cleaning the wall inside the melting apparatus

After spraying 130 degreeC phenol liquid to an inner wall surface through a spray nozzle, and fully wash | cleaning an inner wall surface, the inside wall surface is sprayed by spraying 150 degreeC phenol / bisphenol A mixture liquid (mixed weight ratio: 65/35). It fully washed.

(2) Cleaning the inner wall of the stripping device

Under normal pressure, 130 ° C. phenol was allowed to flow through a spray nozzle attached to the upper part of the device, and after washing the center of the device, 130 ° C. phenol followed by 150 ° C. phenol / bisphenol A mixture (mixed weight ratio = 65/35 ) So that the device wall is sufficiently wetted. The phenol / bisphenol A mixture (mixed weight ratio = 65/35) was then passed through under conditions of 180 ° C. and 10 Torr.

(3) Cleaning the inner wall of the pipe

The phenol of 130 degreeC was made to flow through the piping, and it was wash | cleaned. At that time, care was taken not to exist in the interior wall.

Moreover, it was confirmed by the said washing | cleaning that the amount of oxygen adhering to the inner wall surface of each apparatus and piping is 5 mmol or less per 1 m <^{2> of} inner wall surfaces.

Then, as described above, using a device in which the molten liquid of the crystal additive product and the molten liquid of bisphenol A are in contact with each other, and an apparatus system in which the inner wall surface of the pipe is previously deoxygenated, the purified crystal additive product (molten colored APHA) Phenolic was evaporated and removed in 5), and bisphenol A was isolate | separated.

(Production of Crystal Additives)

A mixture of bisphenol A, phenol and impurity, which is a molten color 50 APHA, obtained by reacting phenol and acetone in the presence of an acid catalyst, was crystallized to precipitate an adduct. This slurry solution was filtered under reduced pressure, and the refine | purified phenol obtained by the method mentioned later was wash | cleaned using 2.5 weight part with respect to 1 weight part of addition products, and the refined crystal addition product was obtained.

(Production of Purified Phenol)

The purified phenol used above was a thing of melt color 6 APHA, and was manufactured as follows. A commercial phenol (water concentration of 0.1 wt%, impurity concentration of 0.05 wt%) was subjected to contact treatment at a temperature of 80 DEG C and a contact time of 50 minutes using Amberlite IR-118H + resin manufactured by Rohm and Haas Co., Ltd. Distillation was carried out at a temperature of 175 ° C and a column top pressure of 560 Torr to recover purified phenol from the column.

(Operation conditions)

Moreover, the operating conditions of the melting apparatus and the stripping apparatus in the above are as follows.

(Melting device)

Temperature: 130 ℃

Pressure: normal pressure

Atmospheric oxygen concentration: 0.0005 vol%

(Striping device)

Temperature: 175 ℃

Pressure: 10 Torr

Atmospheric oxygen concentration partial pressure: 0.0015 vol%

Comparative Example C-6

In Example C-6, the same experiment was conducted except that the inner walls of the melting apparatus, the stripping apparatus, and the pipe were not cleaned.

Next, the molten color at 175 ° C of bisphenol A obtained in Example C-6 and Comparative Example C-6 is collectively displayed in the following table.

Table C-6

number Melt Color of Bisphenol A (APHA) Example C-6 Comparative Example C-6 1080

Example C-7 (Fifth Process)

As a crystal adduct dissolving device, an external heating hermetically sealed container made of SUS 316 was used, and two packing towers made of SUS 304 were used as an evaporation treatment apparatus for the crystal adduct melt, in which SUS 316 filler was filled therein. .

In the melting apparatus, a crystal addition product supply pipe was placed at the top thereof, a melt pipe was placed at the bottom thereof, and the pipe was connected to the middle of the first packed column. In this 1st packed tower, the phenol vapor discharge piping was provided in the tower part, the melt pipe containing bisphenol A and phenol was installed in the bottom part, and this piping was connected to the intermediate part of the 2nd packed tower. The top of this second packed column installed a pipe for discharging the mixed vapor containing phenol, steam and a small amount of bisphenol A, which was connected to the cooling condenser shown in FIG. In addition, a bisphenol A discharge pipe and a steam supply pipe were installed at the bottom of the column of the second packed column.

Moreover, the heating coil which distribute | circulates a heating steam was arrange | positioned in each bottom part of said 1st packed tower and a 2nd packed tower. In addition, all the above-mentioned pipings were all made of SUS316.

Next, in the apparatus system configured as described above, the inner wall surface of the melting apparatus, the inner wall surface of the first filling tower and the second filling tower and the filling material surface thereof, piping between the melting apparatus and the first filling tower, The piping between the first packed column and the second packed column and the bisphenol A discharge pipe disposed at the bottom of the second packed column were washed as follows to remove the adhered oxygen.

(1) Cleaning the inner wall of the melting apparatus

After spraying 130 degreeC phenol liquid on the inner wall surface under normal pressure through a spray nozzle, and fully wash | cleaning an inner wall surface, it sprays 150 degreeC phenol / bisphenol A mixed liquid (mixed weight ratio = 65/35), and fully wash | cleans an inner wall surface. did.

(2) Cleaning of the inner wall and filling surface of the packed column

Under normal pressure, 130 ° C. phenol was introduced into a spray nozzle installed at the top of the device, followed by washing in the device, followed by 130 ° C. phenol followed by 150 ° C. phenol / bisphenol A mixture (mixed weight ratio = 65/35). The device wall and the filler surface were circulated sufficiently to get wet. The phenol / bisphenol A mixture (mixed weight ratio = 65/35) was then passed through under conditions of 180 ° C. and 10 Torr.

(3) Cleaning the inner wall of pipe

The phenol at 130 ° C. was passed through the pipe and washed. At that time, care was taken not to exist in the gas phase wall surface.

In addition, by the above cleaning, the amount of oxygen adhering to the inner wall surface of the melting apparatus, the inner wall surface of the packed column and its filler, and the inner wall surface of the pipe was found to be 5 mmol or less per 1 m ^{2 of} surface area.

Next, using the above-mentioned apparatus system in which the surface of the melting apparatus, the packed column, the filler, and the pipe which the molten liquid of the crystal additive adduct and the molten liquid of bisphenol A come into contact with each other is previously deoxygenated, Phenolic was evaporated and removed by color APHA: 5), and the bisphenol A was separated and recovered, and cooling condensation treatment of the mixed vapor obtained in the top of the second packed column was performed.

(Production of Crystal Additives)

A mixture of bisphenol A, a phenol and an impurity 50 mol of APHA obtained by reacting phenol and acetone in the presence of an acid catalyst was crystallized to precipitate a crystal adduct. The slurry solution was filtered under reduced pressure to obtain a solid crystal adduct. The purified phenol obtained by the method described later was washed at a ratio of 2.5 parts by weight based on 1 part by weight of the adduct, thereby obtaining a purified crystal adduct.

(Production of Purified Phenol)

The refined phenol used above was of melt color 6 APHA and was prepared as follows. A commercial phenol (water concentration of 0.1 wt%, impurity concentration of 0.05 wt%) was subjected to contact treatment using a Amberlite IR-118H + resin, manufactured by Rohm and Haas, at a temperature of 80 ° C. and a contact time of 50 minutes, and the resulting product was subjected to a distillation column Distillation was carried out at a temperature of 175 DEG C and a column static pressure of 560 Torr to recover purified phenol from the distillation column.

(Operation conditions)

In addition, the operating conditions of the melting apparatus, the first packed column, the second packed column, and the cooling condenser system in the above are as follows.

(Melting device)

Temperature: 130 ℃

Pressure: normal pressure

Oxygen concentration in the atmosphere: 0.0005 vol%

(First charging tower)

Temperature: 170 ℃

Pressure: 10 Torr

Oxygen concentration in steam atmosphere: 0.0015 vol%

(Second charging tower)

Temperature: 180 ℃

Pressure: 10 Torr

Steam supply: 0.08 kg per kg of melt

Oxygen concentration in steam atmosphere: 0.0002 vol%

(Operation conditions of the first cooler of FIG. 6)

(1) stripping gas introduced into the first cooler (1) in line (3)

Pressure: 10 Torr

Temperature: 180 ℃

Composition: Bisphenol A 25 wt%, Phenol 25wt%, Steam 50 wt%

(2) a first cooling medium (phenol) introduced in line (5)

Temperature: 50 ℃

Cooling medium / stripping gas weight ratio: 6

(3) Recovery rate of bisphenol A from stripping gas in the cooler 1: 100%

(Operation conditions of the second cooler of FIG. 6)

(1) uncondensed gas introduced into the second cooler in line (8)

Pressure: 10 Torr

Temperature: 51 ℃

Composition: 65 wt% phenol, 35 wt% steam

(2) a second cooling medium (phenol aqueous solution) introduced into the second cooler (2) in line (9)

Temperature: 9 ℃

Cooling medium / uncondensed gas weight ratio: 190

(3) Recovery rate of each phenol and steam from uncondensed gas in the cooler (2)

Phenol Recovery Rate: 100%

Steam recovery rate: 100%

Example C-8

In Example C-7, the same experiment was conducted except that the oxygen removal treatment was performed only on the inner wall surface of each packed tower and the surface of the filler.

Comparative Example C-7

In Example C-7, the same experiment was conducted except that no oxygen removal treatment was performed.

Comparative Example C-8

In Example C-7, experiments were carried out in the same manner as in the case of using the packed column without oxygen removal treatment on the inner wall surface and the filler surface of each packed tower.

The molten color at 175 ° C of bisphenol A obtained in each of the above Examples and Comparative Examples is collectively shown in the following table.

Table C-7

number Melt Color of Bisphenol A (APHA) Immediately after melting Example C-7 Comparative Example C-8 Comparative Example C-7 Comparative Example C-7 1015200200

Example C-9 (sixth process)

The reaction mixture obtained by reacting phenol and acetone in the presence of an acid catalyst was subjected to multistage crystallization. Bisphenol A-phenol crystalline adduct whose melt color was APHA 5 was partially diluted with purified phenol, and heated to 130 ° C. to give 30 weight of bisphenol A. It was set as the phenol solution containing%.

This phenol solution was used as a raw material liquid and processed using the evaporator system shown in FIG.

Next, the main operating conditions of the apparatus system shown in FIG. 6 and the composition of the liquids passing through the main line are shown below.

(1) first evaporator (1)

(i) External heater temperature: 170 ℃

(ii) Internal pressure: 20 Torr

(2) second evaporator (2)

(i) External heater temperature: 180 ℃

(ii) Internal pressure: 10 Torr

(3) third evaporator (3)

(i) External heater temperature: 180 ℃

(ii) Internal pressure: 10 Torr

(4) in bisphenol A passing through line (12)

Phenolic content: 2.7 weight%

(5) bisphenol A passing through line (16)

(i) Phenol content: 23wt ppm

(ii) Melt color: APHA 20

(6) Steam feed through line 15: 0.04 parts by weight per 1 part by weight of bisphenol A through line 14

Comparative Example C-9

When the operating conditions of the first evaporator 1 were 190 ° C and 10 Torr, the phenol content in bisphenol A passing through the line 12 was reduced only to 7% by weight, and the operation of the first evaporator was unstable.

Comparative Example C-10

When the temperature of each external heater in the second evaporator 2 and the third evaporator 3 was set to 200 ° C., the molten color of the product bisphenol A passing through the line 16 became APHA 45 and the phenol content was 70 ppm. .

Example C-10 (seventh process)

Bisphenol A-phenol crystalline adducts having a melt color of APHA 5 and partially diluted with purified phenol under substantially neutral conditions (pH 5.05) obtained by multi-step crystallization of the reaction mixture obtained by reacting phenol and acetone in the presence of an acid catalyst. It heated to 130 degreeC and made it the phenol solution containing 30 weight% of bisphenol A.

This phenol solution was used as a raw material liquid, and it processed using the evaporator system shown in FIG.

Next, the main operating conditions of the apparatus system shown in FIG. 6 and the composition of the liquids passing through the main line are shown below.

(1) first evaporator (1)

(i) External heater temperature: 170 ℃

(ii) Internal pressure: 20 Torr

(iii) Oxygen concentration in the atmosphere: 0.0010 vol%

(2) second evaporator (2)

(i) External heater temperature: 180 ℃

(ii) Internal pressure: 10 Torr

(iii) Oxygen concentration in the atmosphere: 0.0030 vol%

(3) third evaporator (3)

(i) External heater temperature: 180 ℃

(ii) Internal pressure: 10 Torr

(iii) Oxygen concentration in the atmosphere: 0.0030 vol%

(4) bisphenol A via line (16)

(i) Phenol content: 29 wt ppm

(ii) Melt color: APHA 15

(5) Steam feed through line 15: 0.04 parts by weight relative to 1 part by weight of bisphenol A through line 14

Example C-11

In Example C-10, the same experiment was conducted except that 20 wt ppm of the additive shown in Table 8 was added to the phenol solution containing bisphenol A as a raw material. This experiment was carried out through the line 16, and high purity bisphenol A (APHA: 10, phenol content: 27 wt ppm) was obtained.

Next, using the thermal stability test (test A) which keeps this bisphenol A heated at 175 degreeC for 0 hours or 2 hours in air atmosphere, and the accelerated thermal stability test (test B) which blows air at 175 degreeC for 2.0 hours, The color of was evaluated. The results are shown in Table C-8.

Table C-8

Example C-12

A mixture of bisphenol A, a phenol and an impurity of molten color 50 APHA obtained by reacting phenol and acetone in the presence of an acid catalyst was crystallized in multiple steps to precipitate a crystal adduct. The slurry solution was filtered under reduced pressure to obtain a solid crystal adduct. The purified phenol obtained by the method described below was washed at a ratio of 2.5 parts by weight based on 1 part by weight of the adduct, and then the crystal adduct (color: APHA 5 to 10). , pH 5.05 or less).

Next, 1 part by weight of purified phenol was added to 1 part by weight of this crystal adduct, and the resultant was melted at 130 ° C., and then the obtained melt (pH 5.05) was evaporated in the same manner as in Example C-1 to obtain high-purity bisphenol A (purity 99.96 wt%). ) The phenol content of this bisphenol A was 30 wt ppm or less, and the melt color was 15 APHA.

In addition, the refined phenols used above were of melt color 6 APHA, and commercially available industrial phenols (water concentration of 0.1 wt%, impurity concentration of 0.05 wt%) were used at 80 ° C using Amberlite IR-118H + resin manufactured by Rohm and Haas And contact treatment at 50 minutes of contact time, followed by distillation at a distillation column bottom temperature of 175 ° C and a tower static pressure of 560 Torr.

Example C-13

Continuous condensation of the stripping gas was carried out according to the system diagram shown in FIG. The operating conditions of the 1st cooler 1 and the 2nd cooler 2 in this case are shown below.

(Operation condition of the first cooler)

(1) stripping gas introduced into the first cooler 21 from the line 23

Pressure: 10 Torr

Temperature: 180 ℃

Composition: Bisphenol A 25 wt%, Phenol 25wt%, Steam 50 wt%

(2) a first cooling medium (phenol) introduced from line 25

Temperature: 50 ℃

Cooling medium / stripping gas weight ratio: 6

(3) Recovery rate of bisphenol A from the stripping gas in the cooler 21: 100%

(Operation condition of the second cooler)

(1) uncondensed gas introduced from the line 28 to the second cooler 22

Pressure: 10 Torr

Temperature: 51 ℃

Composition: Phenolic 65wt%, Vapor 35wt%

(2) a second cooling medium (phenolic aqueous solution) introduced from the line 29 to the second cooler 22

Temperature: 9 ℃

Cooling medium / uncondensed gas weight ratio: 190

(3) Recovery rates of phenol and steam from uncondensed gas in the cooler 21

Phenol Recovery: 100%

Steam recovery rate: 100%

By the method of the present invention, it is possible to produce high quality crystal adducts with high efficiency, and to precipitate high quality crystal adducts having a low content of microcrystalline adducts in depositing crystal adducts in a crystal column, In preparing bisphenol A by evaporating off the phenol contained therein, a high-quality bisphenol A having excellent color and no coloration of the melt is obtained, and when the bisphenol A is produced by evaporating off the phenol contained therefrom from the crystal adduct. Coloring of bisphenol A by heating in evaporation can be prevented. In addition, the stripping gas obtained when stripping the phenol-containing bisphenol A can be condensed without depositing the solid bisphenol A and phenol.

Claims (3)

A method of condensing a stiffening gas containing a phenolic compound, bisphenol A, and steam obtained by steam stripping a mixed melt of phenol and bisphenol under a low pressure of 30 Torr or less, wherein the stripping gas is 30 torr. The stripping gas is brought into countercurrent contact with a first cooling medium made of phenol or a phenol containing bisphenol A under the following low pressure conditions and under temperature conditions in which the vapor is maintained as a gas and a portion of the phenolic compound is maintained as a liquid. The first cooling step of condensing substantially the entire amount of bisphenol A and a part of the phenol contained in the same, and obtaining a mixed gas of uncondensed steam and phenol, and the mixed gas obtained in this first cooling step is 30 Torr or less. A second solution consisting of an aqueous solution of phenol under pressure conditions and under temperature conditions condensing substantially the entire amount of the mixed gas Each medium is brought into contact with counter-current, condensing treatment of the stripping gas comprising a second cooling step for condensing a substantial amount of the mixed gas. The method according to claim 1, wherein a part of the condensate of the mixed gas obtained in the second cooling step is used as the second cooling medium. The method of Claim 1 or 2 whose cooling temperature in a 1st cooling process is 42-90 degreeC.